85 6.9 IDI Will not run

[BMadScientist]

Good Evening. I’ve got a 1985 F350 with a 6.9 as the title suggests. I bought the truck a little while ago and up until now it’s been fine. The truck has a R&D Performance RD2-80 aftermarket injection pump. The truck had a Holley Black electric fuel pump on the frame as a lift pump which has a max output pressure of 14 psi. The pump went out a few days ago so at the recommendation of a friend I put a new body style 7.3 power stroke Bosch lift pump on so I would later have the ability to run waste oil, and replaced the fuel filter. I was not aware of the pressure output of that pump (60+ psi) and went ahead and plumbed everything in and found that the truck ran like ****. Bled the fuel lines, checked for air at the pump return port with a clear line and found no air bubbles. The truck would kinda idle ok but has no power, when pushing the pedal to full throttle, the rpms would slowly rise to around 1500(guessing, no tachometer) where it would sit for around 3 seconds before rpm’s raise all the way to what I assume is fuel cutoff at 3800 rpm. I did some research and found that it seems the stock injection pump wants around 5-12 psi of fuel at the inlet. I’ll save the details of this debacle but I put a bypass style regulator on the truck which allowed me try and regulate pressure down to between 4.5-9 psi at which point the truck basically wouldn’t run, it would only idle with at full throttle and die as soon as you let off the throttle. Cranked the pressure regulator all the way closed and blew up my pressure gauge so assume I was getting the full 60 psi of fuel pressure again and it was back to having no power and raising to 1500 rpm and then rocketing off to 3800 rpm. I’ve got another fuel pressure regulator on it now and can crank fuel pressure up between3-20 psi and if I change the spring anywhere between 3-70 psi. Frankly I’ve been at this for 3 days now and I’m throwing my hands up and pleading for help. Did I damage something inside the pump? Is there some crazy inlet pressure that I’m not aware of that’s specific to the R&D pump that I’m not aware of? Is there something I’m overlooking?

 

[Olds64]

With that PSD fuel pump putting out too much pressure you're shooting yourself in the foot before even trying to start the truck. Replace the fuel pump with at least a parts store cheapie and then see if you can get the truck to start.

Here's one that's less than $100 on Summit. You could probably get one even cheaper on Amazon.

Pardon Our Interruption

Better yet, get a Facet Duralift electric fuel pump. Here's one that's well reviewed for our IDI trucks.

Facet Dura-Lift 12v Fuel Pump, 1/8 NPT, 9-11 psi, 120" lift | Pegasus Auto Racing Supplies

The Facet 40222 Dura-Lift Fuel Pump can draw fuel from up to 10 feet away. Great replacement for the lift pump on 83-94 Ford diesel trucks and vans.

www.pegasusautoracing.com

Be wary of cheap imported imitations of the Duralift pump.

 

[BMadScientist]

I appreciate the reply Olds64 but can you tell me how either of those pumps are currently better than my regulated setup right now. Flow is more than adequate and pressure is regulated to within spec. I’m not trying to cause an argument or anything but I fail to see how the Facet pump would help me here. Regardless I was talking to a couple of injection shops today and I’ll be planning to pull the pump out and pull it apart and do some investigating.

 

[asmith]

Two things first the facet pump is definitely not recommended anymore. Their quality has fallen off a lot and they really don't flow enough for our trucks.

Second I am not an IP expert but it sounds to me like something is messed up internally. 60+ psi is a big difference from 11 psi. I would be getting in touch with Justin at R+D to see if he can point you in the right direction as to what could be the issue.
Are you sure you have it regulated down enough now?

 

[BMadScientist]

I’ve been in contact with Justin, when I talked to him last week he had said that there probably wouldn’t be any issue inside the pump had I put 60 psi to it but it would just run like crap. I’ve put a new high quality fuel pressure gauge on the truck so I know what kind of pressure I’m getting out of the regulator and I can tell you for a fact the truck will not run with anywhere in 5-12 psi of fuel inlet pressure.

 

[IDIBRONCO]

Maybe you should try calling Justin again. I'm also no IP expert, but he is.

 

[BMadScientist]

That’s been my plan, I called his shop today and was talking to the Katie there for a little while but never got around to making another call to pick Justin’s brain.

 

[onetonjohn]

Maybe dumb question, but what's the correct flow volume for our trucks @ the 5-12psi? What's the flow rate of the pump you have at 60psi? I'm assuming the regulator bleeds off pressure by sending the flow fuel back to the tank (reducing volume), correct? I'm not an expert, but if Justin said the 60psi shouldn't have killed your pump, my best guess is your not getting the volume you need.

 

[BMadScientist]

I thought about that as well but I believe that the stock lift pump would have put out between 30-50 GPH and the 7.3 power stroke lift pump puts out between 50-52 GPH at 60 psi. I would have figured that this would have been more than adequate. I’ve put 3 different fuel pressure regulators on this truck and the first one was a return less regulator which would have put all that flow right to the pump. I talked today with Justin and I rerouted my return line as per his recommendation to right back to the lift pump inlet. I can only seem to get the truck to kinda idle with the throttle to the floor with inlet pressure at around 20 psi. I pulled the governor top cover off and found a small amount of shavings in there, not a full blown disco party but shavings all the same. I ran the truck a little with the top cover off and I’m not worried that the fuel shutoff is sticking and choking the engine down. I’m also talking to Justin he said that there may be some flavor of issue with the fuel advance piston so I played with the mechanical advance lever for a while too and got nowhere. There’s not plumes of smoke coming out of the exhaust like it’s got timing way off but it’s putting thin black smoke which it didn’t do when the truck was running good. I can’t explain very well but I concur that there may be some type of fuel starvation inside the pump. I can kinda get the truck to barely idle with the throttle all the way closed and then punch it which will slowly raise the rpm’s to just above normal idle where they will sit for a moment then drop back down to a regular idle speed with the throttle wide open. My current plan is to find a semi decent take out injection pump and put that in at least to verify that the pump is or is not the issue. A to Z the truck needs to be able to move under its own power as soon as possible. R&D is at least a few weeks out on pumps, sounds like they’re having some supply chain issues with the company that sleeves their pumps. I’m not wanting to up and drop cash on a brand hammer new reman pump either considering I would only be using it as a diagnostic tool and a get me by pump until I can get something closer to a RD2-110 pump. If I can find a decent core at least I’ll have a local injection shop who I have also been in contact with run through it and recalibrate it the best they can.

 

[BMadScientist]

The truck had a Holley black pump on it when it was running which has a flow rate of 140 GPM so I may try and find another one or a second 7.3 PSD pump and run them in parallel to try and get closer to 100 GPM and see what happens. I’d just have to think that if that’s enough support up to 450 horse on a power stroke it would probably be enough to support the 6.9 IDI even with an upgraded injection pump.

 

[BMadScientist]

I’ve thought about this issue all night, again. I’m not thinking that it’s a fuel supply issue now. I had someone watch my fuel pressure at the pressure gauge which is on the pressure side of the regulator while I was running the engine and there was no pressure drop when the truck was running and would die down. This would indicate to me that the lift pump flow is more than adequate to the injection pump. So I’m back to suspecting the injection pump.

 

[DaveBen]

I would suspect several others have made the same assumption about the feed pump not doing its job. I think there are a couple of reasons for thinking this; You cannot see the results of the feed-pump-to-the-injection- pump. If you have the pressure at the feed-pump, then it is doing its job of feeding the injector pump. The feed pump is easier and cheaper to change then the injector pump. This is why everybogy wants to change it.

 

[BMadScientist]

That’s largely what I’ve figured, it’s not like the injection pumps are unreliable so it’s not like people are throwing new ones on left and right. I think there’s only a handful of guys who really understand what’s going on inside the pumps and I can only imagine they’ve got businesses to run rather than spend a ton of time on the forums. I’ve got a used injection pump of unknown condition coming from the other side of the state so it should be here soon. I’ll probably jam that guy on and see what happens, if it runs I’ll go ahead and look into getting another pump as soon as they’re available at R&D. Id like to optimize my turbo setup and get a RD2-110 like I’ve stated previously. The trucks heavy as all can be, it’s a crew cab dually with a heavy steel flatbed on it. It’s actually got an older RD2-90 pump on it but it’s still got no balls. The turbo on it is a stock GTP38, I’m looking into getting a .84 AR turbine housing for it to try and wake it up a little, at least until I can get ahold of my friends KC turbo off of his 97 F250. Funny enough it’s my best handling vehicle, rides like a Cadillac on rails.

 

[Black dawg]

Do you have return flow out of the pump?

 

[BMadScientist]

There is a little out of the injection pump but not much. I suspect that there is something potentially blocking return flow because there is significant more flow with the top cover off. The truck still doesn’t run right with the top cover off however.