Engine/Transmission (1994 - 1998) hard start, need help getting frustrated

[CEdwards]

When the problem first started I noticed it would take an extra crank or two to start than usual. So put a gauge on the banjo input to the injector pump. Running 22psi at idle. Would drop to 15 then climb to 25 when revved up with no load. Pulled lift pump with steel suction line. Put air pressure to it and I didn't even need a bucket of water to see the leaks. Leaks at steel line, both sides of fuel heater and rubber hose between heater and lp. Can't believe it was running so smooth with so many leaks. Removed heater, replaced steel line with hose barb, replaced all three rubber hoses with marine grade. cleaned pre-filter gasket, new fuel filter, re-test and no leaks. Put everything back together and prime through bleed screw until no more air. Then pumped it up to 28psi with hand pump until I heard the overflow. Start it up. runs good, cuts out a little when revving it up but seems to be coming around. Turn it off, put the tools up, get ready to leave and no start. No pressure, bleed through screw again until no more air. No start but have pressure. Crack injector line and pump and turn over with starter until I finally get fuel. With truck running bleed air out of two more injector lines. Running smooth now. Pressure 28 at idle, dips to 24 when revving then climbs to 32. Test drive is good, let it idle for an hour while I get ready and drive to work. Let it sit for 4 1/2 hours and it wouldn't start again. It's worse now then before I fixed it. Does this pressure reading seem right? What do I check now? Lift pump check valves or something? I have a new overflow valve but my gaskets won't be here till monday and I didn't want to change it until I could tell if it was the pump first.

 

[CEdwards]

Went out and cracked the gauge open and hand pumped the air out cause I forgot to before. I tightened the gauge and hand primed some more so I had pressure built up. Wouldn't start for a long while. When it did start it had 10 psi and slowly went to 0 and died. Am I fighting air or is my lift pump coming and going. I haven't got any pulsation even with needle valve wide open.

 

[DonTX]

Sounds exactly like my frustration with a VP 44 on a lst gen that was bad. Did EVERYTHING else, then finally had the pump rebuilt, started first turn ever after. Just wish I had rebuilt it FIRST! It was a low mileage unit, but the sitting had allowed pitting on some critical pump parts.

 

[CEdwards]

Everytime i start it I have to pump through the bleed screw then get it to idle and have someone feather the throttle while I crack all the injector lines and bleed one by one. Then it will drive fine. I have bled everything in the system 4 times. I'm sure i'm getting it all out and it runs great. Turn it off and come back an hour later and it will have air from the lift pump all the way to the injector. The lift pump was tested with it's fittings in bucket of water, rubber hoses are new. My only option seems to be the steel braided lines going to the tank. I will order new hose and replace all the way in the tank. Any suggestions or ideas? By the way i didn't have this problem when I started working on it. It was just simply taking an extra crank to start and it had 4 leaks on the suction side. I just don't get it.

 

[K5IP]

I guess these fuel pumps do occasionally fail, but is sure sounds like you have an air leak. If you have to drop the tank to replace the steel lines, take time to remove pickup in the tank and check it for leaks also. If this seems ot occur morfe with a low tank of fuel, it might provide an indication of a pickup tube leak.

By the way, the injectors are supposed to be self bleeding. Every time I open up the system on my 95, it will run rough for a sew minutes but then clear up, no injector bleeding needed.

Rog

 

[CNolen]

check the preheater. I was having some similar problems, but when I took the preheater out it fixed it. I guess they leak often. I have a fuel system write up if you want it.

 

[bigdaddydieseldan]

you don't need that fuel preheater it doesn't to a damn thing just another source for air leaks ! have you hand primed the lift pump and made sure that you have fuel pumping all the way through the injection pump the feed and return side ? :{:{:{:{

 

[CEdwards]

In my first post I said I removed the fuel heater and replaced everything from the steel lines from the tank forward and tested with air pressure and bucket of water before re-assembly. Saturday I stripped the bleeder screw. Took out the banjo and JB welded the bleeder screw in and let it setup overnight. I can still bleed it at the gauge line. Sunday morning took some more fuel line and ran it from suction fitting on prefilter to a bucket. Started it up and bled everything real good. Let it sit all day and all night and it started up perfect this morning. Going to cut the steel line by the tank and try that first. If the leak isn't in that section I will drop the tank. I'll post back when I find it. I must have caused a new leak when I was replacing the rubber hoses. As a side note I noticed something that might help others out. As K5IP pointed out usually it's not neccessary to bleed all the injector lines like I was doing. I noticed that air just kept coming out and it seamed to take a long time to bleed and the pressure seemed weak. It would just kind of dribble out the injection line. After running on the bucket I didn't get any air out the injection line and it would squirt out hard as soon as I cracked it open. So it seems that if you do get frothy fuel and not a good squirt then you are probably pumping air even though the truck was running fine after bleeding the lines.

 

[CEdwards]

Found it. Quick disconnect was leaking and so was the new rubber hose to steel line connection. Replaced everything with new hose from tank to pump and it runs smoother than ever. I have learned several things that may help others.

1) Just because it's running and doesn't cut out doesn't mean there is no air in the system. My truck was running good even though frothy fuel would keep coming out the injector line when cracked. If it doesn't squirt out a spray with no bubbles then something is wrong even if it is running alright.

2) don't trust any fittings not to leak. Like a lot of people here I carried a set of marine grade hoses from larry b just in case I needed them, but that wasn't the only thing leaking. The steel line from the suction of the pre-filter that goes up behind the fuel filter bracket was leaking at the crappy factory fitting with the plastic ferrel and it was tight. Even though I removed the heater the gasket was still leaking. I had to take it off and clean up the surface with emery cloth and reassemble. The short rubber hose btween LP and heater was also leaking. Two more leaks going back to the tank. The only way to be positively sure nothing leaks is to take it all off and pressure it up and put it in a bucket of water.

3) If you want to make sure it doesn't leave you stranded somewhere then do a little preventative maintenance. Remove all the lines from tank to pre-filter. Install a 3/8 pipe by 3/8 hose barb in the top of suction inlet on LP. Run marine grade rubber to steel line by tank. I don't know how everyone else is doing it, but the 3/8 hose was a little big for the steel line and it leaked. I ran 3/8 behind the cab to 1/8 inch pipe nipple. Then 5/16 hose from the pipe nipple to the steel line. This gave me a much tighter leak free fit. I double checked everything with air before assembly to make sure. The short hose between LP and heater can be replaced with about 18" of 1/2", just put a long curly q in it to make the turn so the line doesn't kink.

4) Breakdowns can be especially stressful when towing somewhere. As a backup I carry 10 or 12 feet of 3/8 hose. I have removed the anti syphon ball in the fill up tube to the tank. Just pull the big rubber hose off the top of the tank and beat the green ball out of it. This way if something gives out like the pickup in the tank or anything in the line you can stick one end in the fill hole of the tank and the other end on the 3/8 hose barb on the suction. It will at least get you home. I tested this and it does work good.

If I would of had a vp44 instead there is no telling what would have happened. Truck was running fine with proper pressure and still running on air. Hope this might help someone else out. Everyone with a second generation will go through this eventually.

 

[K5IP]

CEdwards,

Good post. It nice when someone follows up when they find the problem.

Rog

 

[Missouri Mule]

I agree nice to hear the problem was fixed. It would be nice to hear if wasn't fixed also.