7.3 IDI running issue

[BigfootIDI]

. Hi. I have a 1989 Ford F-350 7.3 liter IDI. My question is. My truck has about 150,000 miles on it and freshly rebuilt injection pump. The truck starts fine but idles rough, Runs fine at cruising speeds but runs rough after hard acceleration. Truck has new fuel filter, air filter, and return lines. I have also ran 2 bottles of injector clean through it 1 through the tank and 1 in new fuel filter. No change at all. Any advice, recommendations or possible fixes would be appreciated. Thanks.

[3TreeGuy]

how is ur fuel/water separator? Is it full of water? Or maybe your sucking air from somewhere between the tanks and the motor. Thats the only thing i can think of man.

[BigfootIDI]

I drain the fuel water seperator every week. Where I live diesel fuel ain't all that great.
Any pinpoint locations as to were it might be drawing air into the system.

[3TreeGuy]

Idk man, maybe one of the rubber fuel lines along the frame have a crack in it or your return line that goes to your Injector pump. I know you said you replaced all of the return lines, Or maybe your fuel pump is going out? thats all i can think of right now man Hopefully someone else will chime in their opinions.

[Links56]

Does it smoke at all while its running rough? Crack each one of the injector lines one by one while it is running rough If it smooths out then you have a problem with that injector most likely.

[BigfootIDI]

Truck does not smoke while running rough, but has strong raw fuel smell through exhaust. Also truck emits a black puff of smoke when shifting gears after accelerator let off.

[BigfootIDI]

Thanks 3treeguy. truck has new clear injector pump return line. Also no visible air bubbles in return fuel. Would the lift pump starving the injection pump from fuel cuase this issue? thanks again

[FORDF250HDXLT]

i don't know the answer to your question,as im new to diesels myself.
but i can tell you,after replacing the fuel lines from and to the engine/tanks.it idle's much smoother now.
i,like you,replaced the injector lines first.
i did also install an electric fuel pump at the same time i changed tank to engine hoses too.so i wasn't sure if electric is simply more steady at idle or if i had air intrusion lol.
im just doing maintenance/upgrades while i find the perfect used dump bed.
i figured,with such age,the lines are bound to rust/split/leak soon enough anyway,and i wanted to prevent the brake down before it happened.
i went with all rubber fuel rated hose,wire tied it up all good along the frame rail,and re routed away from the exhaust manifold on the delivery.i ran it down beside the starter cable,under/beside the oil pan out of the way better.

edit.
oh wait,yeah i think i do know actually,
if you where to unhook the delivery line from tank to fuel lift pump,and run a short hose from the pump from a diesel jug,and the truck idles smooth,then you would know your sucking air from the delivery line somewhere.
if it still runs rough from the jug,then someone else would have to help ya figure out if its injector/ip pump/weak lift pump etc/or air some other place.
id do that that first though.(well,i replace old brittle stuff like this myself lol.but you know what i mean. )

[Dave Sponaugle]

Strong fuel smell in the exhaust is pointing to injectors that are not closing.

Probably has some white smoke right after you start the engine as well if it is a bit cold where you live.

[BigfootIDI]

yes this truck does have a litlle white smoke after start up especially when cold.
would this cause my missing issue as well and any recommendations as to what brand injector to run and removal procedures.
any more advice would be appreciated
thanks

[3TreeGuy]

MIne does the same thing. I think mine needs injectors because you can smell the fuel from 20ft away! And ive got stock injectors.

[Dave Sponaugle]

1989 shows B, BB, C or D injectors
1983 shows A or AA injectors

For all intents and purposes injectors are wear items.
And most should be changed before 100,000 miles.

6.9 Ford Diesel parts Fuel Injection Turbocharger

24 dollars each for new Delphi injectors with code A, B, BB, C or D is a hard price to beat.

[rhoades79]

Darrell here with a 94 non turbo F-350.
Wanted to jump in for a little help and hopefully spur other conversations.
The truck starts right up and sounds fine for about 5 seconds and dies, then I need to wheel it over for a while untill it starts again.

After reading this thread I took a look under the truck and found the steel lines are wet, so there must be a leak. Leaking down what presure was in the line causing the truck to stall after starting?

Question, should the mechanical pump hold this pressure?

I am putting on rubber lines this weekend and saw where FORDF250HDXLT install an electric pump. What size and do you need a regulator?

Thank you for your help!
Have a GREAT day!
Darrell

[starmilt]

Bigfoot I will agree with Dave and if it runs good cruising and under hard excelleration it will not be an air leak between the tank and pump.

Rhoades if it starts then dies but runs good when you get it started you have air intrusion. it starts on what fuel is in the Ip then dies before the filter fills up again.
This is a killer on the starter and needs to be corrected.

Most common problem areas are the retorn lines.
the fuel heater on the filter header.
The schrader valve itself.
The water seperator on the botton of the filter.

Less common places.
The fuel line from the filter header to the IP.
the fuel pump itself.

Any where you find a damp spot will be an air leak but air will leak where diesel will not,so you might not find it visually.

[rhoades79]

Thank you starmilt,
Yes the fuel line from thetank selectorto the filter tower is wet. and an occasional drip at the middle of the engine cross member. That will be repaired tomorrow.

The top of the filter tower is also wet...
If I understand, is the fuel heater the top wire? Is this repairable? Or do I need a new filter tower. I'm hoping its just an O-ring that I would need to replace?

I did change the filter a couple months ago and the problem revealed itself a couple weeks ago.

The water separator seems fine, I unscrewed it and fuel came out and not wet under that area.

Thank you again for your courteous and helpful response.
Darrell