6.9 IDI running like crap

[CarterDawson]

Hey guys. First time posting on here. I have a 1986 F250 that I bought out of a barn. Been sitting for 10 years. I got it going. Then swapped it from 2wd auto to 4x4 manual zf5. Truck was EXTREMELY gutless. Couldn’t pull a slight hill without being floored in 3rd. And I was floored in 4th just going 50 down the road. Anyway you get the point. GUTLESS. So I put a new injection pump, and injectors in. And HOLY SMOKES this things got some guts!! I’ve been hauling trailers, driving to Portland and back getting 18mpg going 70mph. In a 40 year old truck on 35s. Not bad.

Well about a week ago I’m hauling an old Chevy. And the truck starts bucking and cutting out. So I pull over and it runs smooth no problems. So hop back on the road and same thing as soon as I put a load on it, it starts acting like it’s running out of fuel, or sucking air. So I pull over and let my friend pull the trailer the rest of the way with his truck. Checked for air, and nothing in filter housing, or injection lines.

After unhooking truck, it runs great no problems! Tons of power. Then I haul the trailer home unloaded, no problems! I put a new fuel filter in and it drove great for another 400 miles no problems! Hauling! Good power. Then it starts acting up again. And it’s just getting worse. So here’s what I know.

Truck acts up ONLY after it’s warmed all the way up! And been run uphill/ or with a load on it. As in foot in the throttle. After problem is initiated it does this at any rpm uphill or downhill. Unless I’m not moving, (stationary) then I can rev on it no problem. But while driving It runs like crap, loosing speed and barely staying alive. RPM all over the place. And a little smoke. Push the clutch in and coast. Foot to the Floor it and it jumps between 1000 rpm and 3000 in neutral. Pull over and pop hood. Work throttle by hand and no problems! Hop in and drive and back to the same problem! Super weird.

Only thing I can think of would be bad fuel? But I change between my #3 diesel tank, and my green diesel tank and doesn’t seem to make a difference.

Timing? Weird that this problem came on 1000miles after putting new injection system on with no problems. Why would timing all the sudden be a problem?

Air? It’s not sucking air from what I can tell. No leaks, and no air in filter or injector lines

Bad IP?

I don’t know, I wish there was a simple way to diagnose these motors like the simple gas motors of the era. I feel dumb spending months building this truck just for it to run like **** :/

Sorry for writing book! Wanted to include as much detail as I could to help keyboard diagnoses. Any help is appreciated. Thanks.

 

[Jesus Freak]

Im going to say, either you're sucking air and don't realize it, or your fuel pump isn't keeping up. What are you doing for a fuel pump?

 

[DirtyWood]

Probably unrelated but where did you get the injection pump and injectors from?

If you delete the hard line from filter head to injection pump and convert to fuel hose it makes it real easy to add a fuel pressure gauge so you can monitor inlet pressure at the IP. If your lift pump is of unknown age then it might be worth replacing.

The bucking and cutting out sure sounds like a fuel delivery or air intrusion issue.

I wouldn't feel dumb. You said it was running great until something went wrong.

 

[IDIBRONCO]

or sucking air.

When this happens, you'll get a burst of power and the engine is real clattery.

it starts acting like it’s running out of fuel

This is my guess. I think that your lift pump is going out. If it is, it will only get worse from here. If you keep driving, you'll take out your new injector pump. I had that happen to me last year. My recommendation is to install an electronic fuel pressure gauge between your lift pump and injector pump to be able to monitor the fuel pressure that's coming into the injector pump.

 

[CarterDawson]

Im going to say, either you're sucking air and don't realize it, or your fuel pump isn't keeping up. What are you doing for a fuel pump?

I ordered it off eBay. It is an international NOS part. I paid $110 plus shipping for it, hoping it was gonna last longer than parts store pump. I guess it could be the lobe for the pump as well? We had a truck where that lobe stripped out and we were left stranded

 

[CarterDawson]

When this happens, you'll get a burst of power and the engine is real clattery.

This is my guess. I think that your lift pump is going out. If it is, it will only get worse from here. If you keep driving, you'll take out your new injector pump. I had that happen to me last year. My recommendation is to install an electronic fuel pressure gauge between your lift pump and injector pump to be able to monitor the fuel pressure that's coming into the injector pump.

Ok thanks, I’ll look into doing that. I might just swap a different fuel pump from a different truck over to this one and see if that changes things

 

[CarterDawson]

Probably unrelated but where did you get the injection pump and injectors from?

If you delete the hard line from filter head to injection pump and convert to fuel hose it makes it real easy to add a fuel pressure gauge so you can monitor inlet pressure at the IP. If your lift pump is of unknown age then it might be worth replacing.

The bucking and cutting out sure sounds like a fuel delivery or air intrusion issue.

I wouldn't feel dumb. You said it was running great until something went wrong.

Ok thanks! Lift pump is brand new international NOS pump I ordered off eBay. Injection pump is a rebuild from Pensacola diesel. Injectors were from accurate diesel.

 

[DirtyWood]

Ok thanks! Lift pump is brand new international NOS pump I ordered off eBay. Injection pump is a rebuild from Pensacola diesel. Injectors were from accurate diesel.

Ooh, the infamous Pensacola Diesel. I've never used them but they have a very terrible reputation and lots of people have reported issues with their injection pumps. I know they're cheap but you do get what you pay for. I don't know about the injectors but I doubt they would behave like what you describe.

For injection pumps it's worth paying more upfront so maybe check out Moose Diesel or R&D IDI Performance. I just ordered pump and injectors from R&D myself.

 

[CarterDawson]

Ooh, the infamous Pensacola Diesel. I've never used them but they have a very terrible reputation and lots of people have reported issues with their injection pumps. I know they're cheap but you do get what you pay for. I don't know about the injectors but I doubt they would behave like what you describe.

For injection pumps it's worth paying more upfront so maybe check out Moose Diesel or R&D IDI Performance. I just ordered pump and injectors from R&D myself.

Yeah, I didn’t hear anything bad about the Pensacola Diesel till had already bought it. But I’m not in it much so I could buy another one. Just sucks throwing money at something without knowing the problem. I’ll put a Fuel pressure gauge on it and see what it reads.

 

[CarterDawson]

Do you think I could just tap into the bleeder port for my fuel pressure gauge?

 

[IDIBRONCO]

Injection pump is a rebuild from Pensacola diesel. Injectors were from accurate diesel.

And now we see the problem.

 

[Jesus Freak]

And now we see the problem.

Saw that message coming.....lol

 

[rreegg]

mint looking bullnose. If it might be IP related perhaps do low hanging items first like atf/diesel kleen in the fuel filter overnight. might serve as cheap diagnostics but not sure the failure modes of the Pensacola pumps

 

[DougBoy66]

@CarterDawson I just had a pump from Pensacola and some not so good injectors from swag. I have a fuel pressure guage between the filter and IP. With that set up I could not maintain fuel pressure at highway speed. Pressure would drop to zero and the motor would stumble. I recently installed R&D IP and stock injectors an now it maintains at least 5 psi on the fuel line at all speeds and runs much better at all speeds. I am using a new Carter mechanical pump, same one with both IP's. I wish the Pensacola product was better because it is so readily available but they are just good enough to get you running. It is worth getting IP and injectors from R&D, Classic Diesel Designs or Moose

 

[Nero]

For your reading pleasure

The Oilburners hall of shame

This is not bueno, Diesel Care and Performance gets an "F" rating from the Better Business Bureau: http://www.bbb.org/memphis/business-reviews/auto-repair-services/diesel-care-and-performance-in-millington-tn-44022196 Sadly this outfit continues with poor business ethics and stays in...

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