Truck's stumbling on cold start, thinking it might be a fuel pump issue.

MJGenay

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This issue started about a month ago, where it would catch but take a few seconds of throttle to the floor to get up to normal fast idle speed on a cold start. Now it's at the point where this afternoon the truck won't start. I believe the traditional "air intrusion" symptoms are it fires off then dies, then after a bunch of cranking it fires again. Those are not my symptoms. I have about 3 seconds of cranking on the first attempt without a fire, and then it fires off but not enough to keep the engine going.

Here's the background:
Motorcraft glow plugs and controller are less than a year and a half old.
Two 750CCA or 850 CCA batteries that are about 4-5 months old.
Brand new R&D 80CC injection pump as of like two weeks ago.
Brand new R&D stock injectors as of like two weeks ago.
Timing is set between 8.5 and 9 degrees, closer to 9.
Still running the mechanical fuel pump.
I believe I have good compression; I have never checked the compression but I have minimal blow by.

I'm attaching a video that shows my 4th or 5th attempt at starting this afternoon. Truck partially catches but doesn't kick off enough to run on its own. While this issue has been going on for about a month, it has been much less severe. It seems as though the truck gets closer to starting with my foot off the go pedal vs with the pedal to the floor. Yes, I am cringing using the starter like this. The engine is turning over on the slow side in the video, batteries have been drawn down by all the attempts.

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I have no noticeable fuel leaks anywhere in the engine bay and I am running new R&D rails. I do have dampness on the frame rail back by the fuel selector valve. I figure I have some air working its way in there, but I have no way of accessing it without pulling the flatbed or dropping the tank. My logic is this is a fueling issue; I'd lean towards the mechanical fuel pump is going out, but once the truck is running it runs fine and starts fine when it hasn't been sitting for a day, but I might be misreading the symptoms. Figure it is probably air intrusion back by that fuel selector valve, but before I spend a few hundred bucks on lumber to build a frame to lift the flatbed off, I wanted to check with those who know more than me. I believe I've seen it suggested to run a clear line from the fuel filter housing to the IP to check for bubbles which is something I'm going to give a go once I can grab some clear line.

Frankly, if the concensous is "fueling issue" then I'm going to go the e pump route. I've read up a bit on that, and I believe I have it figured out. Looks as though the Walbro FRB 13 is the way to go nowadays although I'm struggling to find one in stock. I'm thinking about using a Holley Red but I've seen some things that suggest they are less reliable than they used to be. Duralift is another option. Do I need to remove the existing mechanical fuel pump or can I just leave it there? I'm pretty determined to have the e pump installed in the engine bay as to avoid potentially ripping it off under the truck when I'm driving through the woods.
 

KansasIDI

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Frankly, if the concensous is "fueling issue" then I'm going to go the e pump route. I've read up a bit on that, and I believe I have it figured out. Looks as though the Walbro FRB 13 is the way to go nowadays although I'm struggling to find one in stock. I'm thinking about using a Holley Red but I've seen some things that suggest they are less reliable than they used to be. Duralift is another option. Do I need to remove the existing mechanical fuel pump or can I just leave it there? I'm pretty determined to have the e pump installed in the engine bay as to avoid potentially ripping it off under the truck when I'm driving through the woods.
I think it’s a fueling issue, but I don’t really know. You would have to do some digging to find out. I would recommend replacing the mechanical pump for now, they are inexpensive, and if that fixes your problem, then I would recommend getting a Walbro FRB-13. I am yet to see a reported issue with them. I am on the second Holley pump inside of eight months, when this one fails, I will install a Walbro that I have on the shelf. And if I get the time, I will switch it out before then.

It’s rather important that you keep your e pump as close to the tank as possible, they are pushers, not pullers. I would recommend mounting it right after the fuel selector valve.

If your fuel selector valve is the problem, I recommend a GROCO FV65038. They are a manual six way fuel valve. I have one on my 86. Best modification so far if you ask me. They run about $170. You can buy them off Amazon.
 

KansasIDI

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Unless you use a series of check valves, which other members can elaborate on, it is typically not recommended to run both a mechanical and electric fuel pump
 

MJGenay

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Thank you. I had to run to NAPA to warranty my brake booster so I picked up a mechanical fuel pump while there. I haven't dug into how to install it yet but I figure it has to be pretty simple.

Regarding the electric pump, I would just bypass the manual pump. I'm wondering if I can leave the mechanical pump installed, at least temporarily, until I install the block off plate? I'm not sure if it requires diesel going through it for lubrication and cooling.

One of the advantages, besides the reliability, that I see with the Walbro FRB 13 is it specs that it can pull 48" of fuel, so I'm figuring I should be good mounting it on the passenger fender liner?

The fuel selector is completely functional, but I'm not sure if it's leaking or if it is a line going into it. At any rate I'm going to have to stop kicking that can down the road and deal with it in the next couple months.
 

KansasIDI

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Thank you. I had to run to NAPA to warranty my brake booster so I picked up a mechanical fuel pump while there. I haven't dug into how to install it yet but I figure it has to be pretty simple.
Make sure that you get the arm under the cam lobe…
Regarding the electric pump, I would just bypass the manual pump. I'm wondering if I can leave the mechanical pump installed, at least temporarily, until I install the block off plate? I'm not sure if it requires diesel going through it for lubrication and cooling.
It uses engine oil for lubrication. It is a diaphragm style pump, so if it self-destructs with nothing hooked to it, it would probably only result in a small oil leak. Your best bet is to use a block off plate if you go with an e pump.
One of the advantages, besides the reliability, that I see with the Walbro FRB 13 is it specs that it can pull 48" of fuel, so I'm figuring I should be good mounting it on the passenger fender liner?
For one, I think you are gonna have more than 48 inches of fuel line between the fender liner and the front tank, much less the rear tank, and the way electric pumps are designed, you’re better off to get it as close to the tank as possible, otherwise it might not get you enough fuel, and putting it so far away from the tank would open up much more opportunity for air intrusion.

I have a skid plate that I built to protect my electric pump, just a piece of sheet metal. I have my filters down there too.
The fuel selector is completely functional, but I'm not sure if it's leaking or if it is a line going into it. At any rate I'm going to have to stop kicking that can down the road and deal with it in the next couple months.
I would check that out first if I were you, if there’s a leak, it’s likely that you could be getting air in there as well.
 

MJGenay

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Make sure that you get the arm under the cam lobe…

It uses engine oil for lubrication. It is a diaphragm style pump, so if it self-destructs with nothing hooked to it, it would probably only result in a small oil leak. Your best bet is to use a block off plate if you go with an e pump.

For one, I think you are gonna have more than 48 inches of fuel line between the fender liner and the front tank, much less the rear tank, and the way electric pumps are designed, you’re better off to get it as close to the tank as possible, otherwise it might not get you enough fuel, and putting it so far away from the tank would open up much more opportunity for air intrusion.

I have a skid plate that I built to protect my electric pump, just a piece of sheet metal. I have my filters down there too.

I would check that out first if I were you, if there’s a leak, it’s likely that you could be getting air in there as well.
Shoot. I assumed the 48" referred to vertical lift, not lateral. Walbro's website says the following regarding that pump
"Self-Priming (Dry Lift) of more than 48" (120 cm)"


Skid plate is a good idea.

I was hoping to kick the larger, much more time consuming job of dropping that tank or lifting the flatbed down the road until I had more time. My concern is that I have enough air intrusion that THAT is my issue, hence the band aid of the electric fuel pump.
 

MtnHaul

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Just my .02 here but I found trying to thread the bolts for the mechanical pump while keeping the gasket in place was a PITA and switching to e-pump was worth it just to never have to mess with those bolts again. Leaning over the engine with both arms buried while blindly trying to thread bolts is not my idea of a good time. You can always try running directly from a fuel can just to make sure the problem is before the pump. If air intrusion is the issue I recall a thread where the person finally figured out the metal pick-up tube inside the tank had a pinhole in it and was drawing in air. Also, dropping the tanks is not that bad and has to be easier than removing a flatbed unless you have access to heavy equipment.
 

MJGenay

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Okay, I put a new mechanical pump on and that seems to have fixed the issue. We'll see if there are any starting issues tomorrow. I found a boost leak too, a loose hose clamp from the turbo to the housing on the intake, so it definitely is pushing more power. I have a couple questions.

1A.) Do I need to check and potentially adjust the timing? It was blowing grey smoke the first few minutes. I did read that with a e pump providing different flow the timing may have to be adjusted.

1B.) When I timed the engine, I found I had to turn the pump around 1/8" towards passenger side to get the proper timing. Is that normal, or did the ******* before me remove the timing gear and possibly has it one tooth off?

2.) What are the hose fittings on each end of that hard line from the lift pump to the filter housing? I had to put a lot of pressure on that metal line to get it to line up. I'd like to replace it with a rubber hose if that can handle the pressure. I still plan to do a Walbro E pump but I'd like to keep the mechanical pump installed, and bypassed when I install the e pump, in case the e pump fails in the future.

3.) Regarding my brake booster... the replacement NAPA provided is working much better, brakes grab better. I bypassed the vacuum lines going to the cruise control with the intention of removing that. Immediately after bypassing the cruise control, the former, and current brake boosters always "swoosh" when I hit the brakes. If I hit them a second time, no air noise. They work fine. Using the brakes again later causes the same "swoosh".

I plan to drop the tanks, fix whatever leak is back there by the mixing valve, and I probably have to deal with the broken off shower heads too. Fuel sender reads 1/4 past Full when the tanks are full. I never have tried running lower than 1/2 tank.
 

MtnHaul

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As to #2, the hard line from lift pump to filter housing isn't under much pressure at all and can be swapped to 3/8 hose with ring clamps--though I prefer 3/8 fuel injector line clamps. I can't recall for sure but I think the filter head inlet is 1/4 NPT--a site search will find that info quickly. In general it seems that trying to keep the mechanical and the e-pump as options is not the preferred route. I made sure my e-pump install was clean and easy to swap so I just carry an extra pump in my little "roadside assistance kit" that lives on the truck. I keep a set of belts, starter solenoid, fuel pump, fuses, fuel filter, 3/8 hose, and on long trips I toss in a spare starter. Overkill? Sounds just right to me!
 

MJGenay

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Alright, so I have a Walbro FRB 13 on order. Planning to plumb that in down by the tanks when it gets here. Can I wire it to get power off the starter solenoid or is there a better place? I'd like the fuel pump to be key activated.
 

MtnHaul

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Some people use a relay triggered by the FSS connection on the injection pump. I tapped into a wire from the disconnected chime module that was hot with key "on" and used that to trigger the relay(Think it was yellow with red stripe or red with yellow stripe). Once your trigger wire is set you can run a dedicated, fused power wire to the pump. Admittedly I did have a random relay failure where I had to quickly rewire things on the side of the road so now I carry a spare relay. Use spade connectors or similar for easy repair or removal. I would keep the pump on it's own circuit, so to speak, to avoid complicating electrical problems.
 
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