Biting the bullet: Converting to electric fuel pump

[The_Josh_Bear]

I finally took the RV out for a test drive since I put the dial fuel pressure regulator. Having it set to 4.5-5 on the dial was still too high. 2.5-3 seems too low too. So, it's at 3.5 on the dial and I can get it up to 65-70, but it still feels almost like an NA engine, gutless.

I have to hold the pedal to the floor to slowly get up to highway speed when merging on. Since it's not a mechanical pump, it doesn't speed up the more the throttle is pressed, so I have to just floor it and let it slowly wind up to speed. Not ideal, but I'm guessing that's the norm?

Proper retiming might still help it, which I plan to do at Creekside auto west if Dallas (listed in teh OB IDI timing reg). I didn't have the fuel pressure gauge hooked up (lazy me) so I don't know the actual pressure the stock fuel filter was seeing. I could tell a top end speed difference depending on the setting though.

I didn't see any smoke when floored (but that can be hard to see in the mirror) and EGTs are normal... never saw it over 900 when the pedal was being held to the floor even when at 65 (seems to somewhat try to top out at 68 on a very slight hill on the interstate). That's about the EGT with the mechanical pump at highway speeds. But that's still better than the 55-60 it was doing without the regulator. It could probably get to 70+ if I keep holding it to the floor but I was test driving it on a ~1 mile stretch between 2 exits here by the house.

Is your IP maxed out? Assuming the temp probe is before the turbo as it should be you have overhead for more fuel.

 

[Cubey]

Is your IP maxed out? Assuming the temp probe is before the turbo as it should be you have overhead for more fuel.

Maxed out? Dunno. Yes, EGT probe is before the turbo. ATS 085 kits have a factory made probe location and show had a pyro kit either included or optional, so that's where the probe is:

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It had no problem with top end throttle response with the mechanical lift pump, so it must be a too much flow/pressure/timing issue. The last maybe 15% of the throttle barely does anything. Before I put the fuel pressure regulator, it was similar but throttle to the floor maxed it out at about 55-60. Now I can get up to 65+. I touched nothing on the IP. In theory, going back to a mechanical would fix it back to normal..... assuming someone didn't mess with the IP to make it work better with the old worn out mechanical lift pump.

@Thewespaul What do you think? To sum up the past few posts: Lowering the pressure with a fuel pressure helped top end speed from 55-60 to 65+ but it still has to be held to the floor to do so. Also to get up to highway speed, must be floored. Not needed for take-offs from stops, throttle is still acting like it should, it's only the top end that's still screwy. No smoke that I can easily see in the side mirror when driving, normal EGT (900 at 65). With pedal to the floor, it just acts like I have it a 3/4 open or so. Wasn't that way with mechanical. Still a timing issue? Or does the IP itself need tuning to work right with the electrical pump?

 

[Clb]

Perfect job for a Fawcett...

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I pulled it off the 93 due to the lack of pressure , group buy unit,
And put on a red...
It fills the ferd tank just fine.

 

[Cubey]

Perfect job for a Fawcett...

Funny because those are the ones many people say NOT to use because it can't keep up.

Holley Red should, in theory anyway, be enough. The lower the pressure, the higher the flow. Unless the regulator tossed into the mix is helping the timing (allowing better top speed), but is also restricting the flow.

The Holley red chart:

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Before I drive it again, I'll put the fuel pressure test gauge on it again so I can see what it's doing now with the regulator while under load with the pedal to the floor. Without the regulator, it was keeping up the pressure at 5 PSI at WOT at about 55-60mph max.

Maybe I need a higher flow pump. Guess I should have gone with the Holley Black. I wanted something that wouldn't need a regulator, but that's out the window already with this Holey Red. I hate to buy another $230 fuel pump ($212+tax for Holley Black) and not have it work any better due to it being an IP setting or timing issue.

I guess if having the timing done doesn't help it, I'll just go back to a mechanical pump since it ran fine on the highway with that, even when it was weeping fuel to the ground. They cost all of ~$35 with tax at any auto parts store and have a 1 year warranty. It's a nasty job to change (from the bottom anyway) if the new mech pump goes bad and I dread having to worry about lining up the arm with the cam lobe, but I'm starting to think its still better than worrying about this... unless I can get this weird issue sorted out.

 

[genscripter]

I went back and looked at your photo of your two fuel systems tee'd in on the frame rail.

It's extraordinarily complex, which is fine if you like that, but you might want to start isolating systems before tearing it back down to stock.

Can you run it from a diesel can with a hose to the Holley pump to your filter to your IP?

You might want to run it without the pre-filter just for a drive, just to see if that is clogging and making the fuel restriction. I hate those small pre-filters, and that's why I like the clean-able pre-filter screens that the duralift has. Not only can you clean them, but you can see through them to instantly know if your diesel is clogging the system before it even gets to the pump.

Cut out the regulator and all the parallel circuits. Just isolate the diesel can to holley pump to filter to IP. See if you get the same pressure issues and speed issues.

 

[Cubey]

I went back and looked at your photo of your two fuel systems tee'd in on the frame rail.

It's extraordinarily complex, which is fine if you like that, but you might want to start isolating systems before tearing it back down to stock.

Can you run it from a diesel can with a hose to the Holley pump to your filter to your IP?

You might want to run it without the pre-filter just for a drive, just to see if that is clogging and making the fuel restriction. I hate those small pre-filters, and that's why I like the clean-able pre-filter screens that the duralift has. Not only can you clean them, but you can see through them to instantly know if your diesel is clogging the system before it even gets to the pump.

Cut out the regulator and all the parallel circuits. Just isolate the diesel can to holley pump to filter to IP. See if you get the same pressure issues and speed issues.

Well if you ignore the return line stuff, it's not too complicated:

[front tank]-[pre-filter]-[Holley red]-[Racor R26P W/S filter]-[stock filter]-[IP]

I redid the return lines some, so the returned fuel goes straight through the tee instead of turning, and I put a check valve to prevent returning fuel from accidentally going to the rear tank. The branch from the tee and that U turn hose is going to the check valve/transfer pump/rear tank's supply line. I can probably rule that out as being a problem, unless the tee is too restrictive for the fuel running straight through it. It's not hard to isolate, since I just have to connect two factory steel lines with a 5/16" hose to delete the transfer pump/tee setup.

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The Racor filter head came off of a junk yard IDI pickup with Banks turbo so in theory it should be fine. It was on the firewall in place of the stock W/S. I have the largest micron (30) element on there. It doesn't list a GPH spec though:
https://ph.parker.com/us/en/racor-replacement-filter-element-spin-on/r26p

This store claims 45gph: https://jwmarinellc.com/product/racor-fuel-filter-water-separator-element-r26p/

Parker/Racor makes (or made?) a drainable W/S fuel filter that fits in place of the stock 6.9 IDI filter. It's listed as 20GPH. I wonder if that's what the Motorcraft FD-811 filter is too, since you'd think they would make the spec the same, since it's exclusively shown as being for 6.9L IDIs.

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I could make the Racor R26p the pre-filter, but I'd have to run a lot of extra hose because there is no other good place to mount it. I have it bolted to the frame where the (missing) stock W/S goes. It's up nice and high, so far less unlikely to get caught on anything I might drive over.

The pic below was with a 2 micron rating element and it WAS causing fuel starving with the mechanical pump.... but it was old and dirty from the truck it came from, so that element was suspect. Not to mention the 35 year old weeping worn out mechanical pump probably wasn't as it's strongest. It would surge randomly under heavy throttle, or something like that. After I got to the next town, I bypassed it and the problem went away.

Hose on the right is the inlet, hose on the left is the outlet.

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So as you can see, it's easy to bypass by just swapping out 2 hose connections, but I seem to recall I tried that already with the new 30 micron filter after the Holley Red was installed. I might have to do it again though, in addition to deleting the pre-filter. Maybe it's a combination of both causing problems. I need to see if I have a long enough piece of 3/8" hose laying around to delete the prefilter. If not, I'll go get some. The pre-filer has been catching some stuff, so I hate to run long term without SOMETHING between the tank and pump.

So.... I guess I'll first try deleting the glass pre-filter and then try the 1 mile interstate run (thank goodness for the extra long on-ramp lane), with the Racor hooked up as it is now, after the pump, just to see if anything changes. That's just a matter of 2 hose clamps and replacing it with a short hose from the steel line from the tank to the pump inlet. That's one of the cheapest and easiest thing to try and like you say, it might be the weakest point as far as the flow. There's a gas station with a bit of semi space due to truck lanes, so I stop there to fiddle with things if I need to after the first 1 mile run, then I can hop back on for the 1 mile run back to the road I started from.

Not far away, I can go on the 2 lane state highway with big hills and not much traffic to further test it, if I end up with good normal top end on the somewhat flat interstate. No point trying that if I can't hardly get to 70+ mph even with the pedal being held to the floor on a relatively flat stretch of interstate.

 

[Philip1]

Another thing you can check is the fuel back pressure in the return system. I used a 3psi gauge teed into the return line next to the ip when checking mine.

 

[Cubey]

Ok, so I removed the glass pre-filter. Seemed the same... but... read on:

The way this thing is geared/tuned trans wise, it doesn't shift to 2nd until around 27-28mph so it sits a long time in 1st. 3rd kicks in around 38-40mph. It's always done it since I've owned it. It's like it's set up mainly for heavy footed highway driving, perhaps towing a car or heavy trailer. Manually shifting works for getting into 2nd sooner, so I often do that in residential areas so I'm not screaming through in 1st gear at 25mph.

Problem is, I sometimes don't remember to put it back to D after a stop.

Sooooo I ended up merging onto the interstate in 2nd and had the pedal to the floor without realizing it. I finally noticed after I got off the exit and tried to take off from the stop sign on a slight hill and it was a bit slow. It wasn't screaming with the pedal the floor in 2nd like you would expect but it would only do 55-60. I took a frontage road but it still felt similar in 3rd gear, so I don't think the pre-filter was it.

That got me thinking, I wonder if the kickdown is screwy. I did mess with a little months ago after the Holley but before the regulator. On this one, for whatever reason, the screw has to be a long way or else it won't reach the throttle lever plate that it must contact. Not sure if that lever got put back on wrong way back the turbo was installed or what.

That's in sharp contract to what's considered normal for IDIs... where the screw barely has to be poking through to make proper contact.

So, I put the screw "in" further so it would make contact sooner and push the kickdown rod sooner. And.. I got up to 70 a fair bit easier. I still had the pedal to the floor in 3rd gear to get there but it made it. I couldn't try any faster since I had a pickup in front of me and by then I was almost at the exit. It sounded like the last tiny bit of throttle pedal travel (5-10%) was giving it a bit more power. Maybe I need to adjust that kickdown screw in even more. Maybe there is something screwy in the kickdown linkages where it's not working properly?

So, I wonder if it's partly a transmission kickdown issue to compensate for the electric pump's flow. The shift points feel the same, nothing changed there.

It could be something is 'wrong' in the trans but since it shifts in all gears without delay or bucking or anything bad like that, I see no point in a pre-emptive rebuild. I just replaced the fluid and filter so that's all fresh. The old was a bit dark but still red, with unknown age/miles.

I have RV roadside assistance including trailer coverage (they won't leave my trailer on the side of the road) if the trans ever does kick the bucket so I'm not too worried about it.

That stupid glass pre-filter was still just barely seeping fuel from one end it looked like, but I think I'll still put it back for now and play with the kickdown lever some more. Or just go buy one of these and be done with it for a while: https://www.autozone.com/filters-and-pcv/fuel-filter/duralast-fuel-filter-ff3330dl/830807_0_0

 

[genscripter]

Did you try running it from a diesel can though? I would basically run the system like this:

Supply side:
diesel can -> hose -> holley pump -> hose -> filter -> IP

Return side:
IP return hose -> diesel can

Take it for a drive and see if it can get up the the highway speeds that you had before.

This cuts out any issues you might have in your tank, pre-filter, and other parts.

 

[Cubey]

Did you try running it from a diesel can though? I would basically run the system like this:

Supply side:
diesel can -> hose -> holley pump -> hose -> filter -> IP

Return side:
IP return hose -> diesel can

Take it for a drive and see if it can get up the the highway speeds that you had before.

This cuts out any issues you might have in your tank, pre-filter, and other parts.

No. How would I even do that? Where could I put the cans?

It seems like it's acting more normal now after I adjusted the kickdown screw in more, so I'll screw it in more again before I drive it again to see if it helps it even more. No point removing stuff if it's a kickdown issue. I'll put a pre-filter back and see if it still gets up to 70 easily. If it does with more kickdown screw adjusting with pre-filter, then it's probably safe to say it's not exactly a fuel system problem.

I know it seems strange but it seems to the case.

 

[genscripter]

No. How would I even do that? Where could I put the cans?

You would have just one diesel can. The supply hose and the return hose go into the same can. You can put the diesel can anywhere you want, but I would just put it next to you. We have vans which have doghouses, so it's easy. Just crack the latches on the doghouse and run the hoses through that.

This is just a temporary test to see if there is something other than the fuel pump and the diesel filter that is causing a fuel restriction on your high end speeds. This isn't a long-term fuel supply suggestion. The advantage of making a temporary diesel can system is, you can actually see the fuel coming out of the return line to see how that is doing, and you can know for sure that your fuel supply is not choked off from the fuel pickup or FSV.

I'm not convinced your kickdown has anything to do with this. I deleted my kickdown linkage when I installed my hypermax turbo, and it didn't make any performance issues at any speeds for me.

 

[Clb]

Refresh our memories on the age \ mileage on the fuel system minus pump junk....

 

[Cubey]

Refresh our memories on the age \ mileage on the fuel system minus pump junk....

73k original miles, more than likely

 

[Cubey]

You would have just one diesel can. The supply hose and the return hose go into the same can. You can put the diesel can anywhere you want, but I would just put it next to you. We have vans which have doghouses, so it's easy. Just crack the latches on the doghouse and run the hoses through that.

This is just a temporary test to see if there is something other than the fuel pump and the diesel filter that is causing a fuel restriction on your high end speeds. This isn't a long-term fuel supply suggestion. The advantage of making a temporary diesel can system is, you can actually see the fuel coming out of the return line to see how that is doing, and you can know for sure that your fuel supply is not choked off from the fuel pickup or FSV.

I'm not convinced your kickdown has anything to do with this. I deleted my kickdown linkage when I installed my hypermax turbo, and it didn't make any performance issues at any speeds for me.

I think it's doing decently now after I removed the pre-filter and adjusted the kickdown. Maybe kickdown had nothing to do with it but it seems odd that it improved after I messed with it.

I will try putting the pre-filter just to see if that makes a difference again though, since I want to protect the pump from garbage. It takes only a few minutes to swap out with almost no fuel loss. There is so much room under there, I can crawl under and be away from the dripping fuel, so I don't get covered in the dripping diesel. Disposable gloves keep it off of my hands too.

I'm not gonna keep doing test drives though, that's just a waste of money/fuel. The first stretch of highway is gonna be going to DFW from AR on I-30, where it's at most rolling hills. As it's acting now, it's good enough to get to the shop for timing, which might just be what it needs to fix it the rest of the way.

Maybe the pressure isn't great in the trans from the old seals and the kickdown being pushed helps it speed up, since that's how kickdown works to trigger a downshift. It has never kicked down to 2nd from 3rd when I floor it, so it might be a trans problem internally, or just very poorly installed/adjusted kickdown linkage. It does look kind of borked near the lever when I push the lever, like maybe it's missing a bushing for the linkage? Beats me. Just saying what I have observed. Messing with the kickdown screw seems to improve the throttle behavior slightly. The motor sounded better too on the last tiny bit of throttle, like it was actually accelerating a little, instead of just staying exactly the same despite being at the floor.

Hmm, I wonder if the opposite might be true... maybe the kickdown is in TOO far and it's stopping the throttle from opening fully. I'm pretty sure I put it in further though today, not out, and it improved the throttle. I'll have to fiddle with the kickdown screw some more to see what's up with that.

My F250 with a newer rebuild C6, if the kickdown isn't adjusted right, it makes a BIG difference, even in lower gears. I fiddled with it back in 2017 for city driving and it made a massive difference in shift points. Once I got it where I wanted it, I have never touched it since. And it's running a cheapo 12D electric pump. Only time it has ever acted funny surging has been on the interstate in WY with big tail wind gusts.

 

[Cubey]

This is going slightly off topic, but since it's directly related problems that showed up right after the electric pump conversion... so I'll post about it here.

It seems my throttle cable may have stretched since the last time I checked it. I had my 12 ton bottle jack in it's original cardboard box holding the throttle to the floor and this is the remaining travel of the lever on the IP:

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Funny that it wasn't a problem for the mechanical pump. Unless it stretched immediately after I converted it, which seems unlikely.

Based on my F250 with the same engine and trans setup (6.9 + C6) without a stretched cable (I just checked it in the same way, almost no play on the lever with the pedal to the floor) the throttle lever travels about mid way before it touches the kickdown screw. The remaining half travel is pushing the kickdown rod. So, as far as I can tell, that's normal behavior since the F250 downshifts like it should. The third quarter of throttle must increase the C6's pressure but doesn't shift it, that last quarter (floored) must do that. Rough estimates of course.

For some reason, the F250's kickdown rod is hitting the back of the IP when it's not being pressed. I mentioned how I thought the RV's kickdown lever was installed "wrong"; well maybe the F250's actually is, hence the linkage hitting the IP. Here is a comparison of the two.

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The RV's (left) is leaning back much further than the F250's (right). The guy I bought the F250 from said the IP was newer, so maybe that explains that. Someone put the kickdown lever back on wrong during IP replacement. The RV's IP is likely 100% original.

So for now, I have adjusted the kickdown screw on the RV so that it just contacts the throttle's lever plate about mid way in travel. I'll just have to see how it behaves on the interstate to see if it needs adjusting again. No big deal, there's no shortage of exits if I need to take one and stop at a gas station or whatever to adjust it. It's harder with a hot engine since EVERYTHING around it is hot and I have to avoid getting burned, but it is doable. I have to reach in blindly with both hands to work an 8mm open ended wrench on the screw's hex head.

I guess I need to budget in for a new throttle cable in the next 3-6 months if the better kickdown adjustment doesn't fix things.