help my dangerous diesel please

[joeymartin107]

1990 f250 7.3 250k idi a/t completely stock from what I can tell. Irecently purchased this vehicle. It ran perfect now I'm having serious/dangerous issues. I have a list of all the new issues that seemed to happen overnight. Like I said it runs great it starts no problem cold warm no matter the case never smokes even under heavy acceleration but now I have absolutely no throttle response it will eventually 5 to10 seconds later kick in and run out ok. If I kill the truck and immediately restart it runs perfect for a matter of ten seconds and then goes back to the scenario at hand. if. I hit the schrader valve on filter housing I have plenty of pressure but it seems to have bubbles in it as well as when I bleed the system I see a few bubbles I have replaced the filter didn't seem to help but I would think with air in the system it would stall... it stalls when in park on deceleration but not while ingear! I can't figure it out I'm fairly knowledgeable on diesel diagnosis but on a much larger, DI scale. Any help would be appreciated

 

[fuzzy1626]

If it was mine I would pull the filter, dump the fuel out and fill with Diesel Kleen or ATF. Replace filter, start engine and let run for 30 seconds. Shut off and let sit overnight. Start and (if it feels safe) drive it hard.

 

[smolkin]

Bubbles at the schrader are not good. Are the fuel tanks above 1/4 filled? Broken pick-up tubes are very common. Fill tanks completely to rule out. By-pass tanks and run fuel from a can to the tank selector valve to rule out clogged pickup. Next in line is the tank selector valve itself, have been known to fail and allow intrusion. By-pass with a piece of hose to rule out. After that, low-pressure fuel pump; if it can't keep up with the IP demand the IP will keep on suckin' until air is pulled into a weak spot in the system (degraded hose, bad 'olive', etc.) Unless the return lines/injector cap o-rings are totally shot, a leak there will usually only cause hard/ rough starts that should even out as the air is purged, so I'm thinking it's getting air in on the supply side.

If it was mine I would pull the filter, dump the fuel out and fill with Diesel Kleen or ATF. Replace filter, start engine and let run for 30 seconds. Shut off and let sit overnight. Start and (if it feels safe) drive it hard.

When you pull the filter, see if it is filled up completely. If not, air is probably getting in before it. The ATF trick has worked wonders for me in the past, will help unstick things in the IP. But you need to solve the intrusion problem first.

 

[joeymartin107]

Alright I have new return lines and caps I have ran atf for about 3 days once or twice a day seems to have slightly helped but hasn't remedied the situation. Thanks for the advice. As for a cracked pickup tube I am strongly pointing at it as a failed component in my system I am going to run the truck on an auxiliary and see if it helps will repost soon!

PS can I buy pass the lift pump and runs fuel line directly to my inj. Pump or do I need the lift pump to produce the pressure for the pump?

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[riotwarrior]

First Welcome to OB, you find it laid back and easy going here. Take a gander in FAQ and Tech section and the hall of shame, thus getting an idea of any unscrupulous vendors. Also please take some time to fill in your signature so we know yer truck details.

It can also be a cracked fuel line from frame to lift pump or bad fuel olives allowing air in.

There should be a thread about clear return lines and where to place them to locate air intrusion.

Might be an issue with fuel select solenoid perhaps???

Tank pick ups are a potential as well.

Again Welcome to OB

Al

 

[icanfixall]

Welcome to the forum. I feel you are sucking air before the lift pump. Try trplacing the short hose from the the frame hard line to the lift pump. The take plenty of flexing and do wear out. Its 3/8 hose with 2 clamps. Also make sure the tanks are at least full or half full of fuel. Most of our fuel tank suction heads have long since broken off. then we run out of fuel around 1/4 tank. That means the last 1/4 tank can't be sucked up because the suction line is broken off and now too short. Its a very common issue and an easy repair with a short piece of 3/8 rubber hose and a clamp. An easier fix is never let the truck run down to the 1/4 tank level. Do you know how many miles are on the pump and injecters. Usually we feel that 125,000 miles is the useable limit for injection pump and injecters. some get more and some get less. Its very difficult to feel the slow degrading of the performance in the fuel system but we sure feel it when we change it out.

 

[joeymartin107]

Ok so here is more info it seems like maybe my pickup tube has a slit or crack when coming to a stop it almost bogs out and if floor the truck it takes longer to accelerate than if I were to gradually accelerate almost like the fluid momentum of fuel has an effect on performance also while bleeding my system I noticed #2 injector and#3gp have compression blowing past what's up with thatn I believe the injector is an easy fix but the glow plug? I just replaced it and it still leaks. Any idea? And input on my air intrusion?

To Icanfixall im unsure of inj. And I. P. Mileage I have had tuck only about 2k miles

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[joeymartin107]

Oh and fuel level has little to no affect

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[icanfixall]

Well thanks for the updates. To fix the leaky injecters try loosening the line nut on top. Thats a 5/8 wrench. then use a 1 inch wrench to tighten up the injecter body. Hopefully that wil fix it. If it does not your going to need to remove the injecter and find out why it leaking. Usually the copper gasket on the bottom leaks if someone tried to reuse it or tried to use 2 of them or didn't install one at all. It just depends. The torque is 35 lbs on the injecter to the head. A little more wont hurt but 100 lbs will.

 

[joeymartin107]

Ok guys after a very thorough inspection of my fuel system I found the problem and resolved it it was the rubber sleeve seal on my main fuel line going into my IP it was seriously worn and letting my system sick air and bleed off when off thanks for all your help and be looking out for me. For questions as well as suggestions

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