Engine/Transmission (1994 - 1998) Another boring fuel problem

[DDennett]

Hello folks, I have searched and searched and definitely come up with some excellent info but at this point I am a little stumped, so here goes.

About a month ago I started my truck and it started to shudder/miss while idling and up through about 2000 rpm. So I did some research and figured out I had a fuel problem. One of the first things I did was check the pre-filter/heater, sure enough when I took the heater electrical connector off it was wet with fuel, so I eliminated the fuel heater, replaced the filter, and figured I would be good to go, no such luck. Next step I made a fuel pressure rig and checked the fp. Well it was low, so I pinched the return line and it spiked, now were getting somewhere its the overflow valve. I replaced the overflow valve as well as the return/supply hoses and the fuel filter since I had it out anyway. The truck runs better but still has the shudder/miss (albeit not as bad), it is most noticeable when shifting from 3rd to 4th I guess since the drop is so big btwn those 2 gears, and now it loses its prime when it sits for more than a few hours. I checked the fuel pressure again and its good 21 psi at idle and about 28psi at 2500rpm with no load. Am I looking at an injection pump issue? This truck only has 105,000 miles so I certainly hope not. Other than some LarryB starter contacts the truck is bone stock. Any input is greatly appreciated, Thanks.

 

[tp0d]

How far did you change your fuel supply line? all the way to the tank? Sounds like you are pulling air (loss of prime). That could also cause a lack of power if the lift pump is pumping air, even a small amount.



I guess its possible a check valve may be failing in your lift pump, but I dont think theres anything wrong with your inj pump. Is it still stock? or modded?



good luck



-j

 

[DDennett]

Everything is stock. I also think its sucking air , but could it be sucking air and still show good fuel pressure? I did not change the lines at the tank, just from the frame to engine, behind the ip, and the elbow btwn the pre-filter and lift pump.

 

[tp0d]

Yep it can still show good pressure. The supply line to the lift pump is a suction line, so it can have a leak and not bleed out fuel. There have been multiple problems with the steel elbow at the top of the fuel tank. Hopefully this isnt the case, theyre not fun to take down. .



-j

 

[Joe G.]

You might want to check the fitting on top of the fuel heater/pre-filter assembly. It has a fiber washer that can go bad. If you can't find anything else take everything from the supply fuel hose to the input fitting to the fuel filter off. Put about ten PSI of air to all of it put together and dunk it in a five gallon bucket of water. Watch for bubbles. You have to block the lift pump push rod so it won't blow out. If it's not in place correctly you will get air bubbles from the weep hole in the lift pump.

 

[Extreme1]

I had similar problem, it turned out to be one of the "quick release" fittings on top of the tank. I took them off and just slid the hoses onto the plastic nipple.

 

[DDennett]

Alright, so I guess I am still looking at a leak somewhere on the supply side, that is a relief. I am going to pick up a new gasket for that supply fitting on Monday and start there, if no joy I will check the lift pump as Joe G. has suggested. Thanks again for all the advice, it has given me a fresh perspective, which is exactly what I needed. I will post my findings when I find them.

 

[Hammer]

Hmmmm. .

Can't believe that with it being a 12v no one has told you to check the fuel return line. The return line from the P-Pump runs off the overflow valve on the back side of the pump under the intake and back to the rear of the motor. About where the fuel filter cannister is there is a small piece of rubber hose which ALWAYS goes bad(drys out,cracks,leaks and sucks air). You have to first pretend your Gumby,snake your arm under the brake master cylinder,along the bottom of the fuel filter cannister and feel around until you find it. Its no easier to change from the bottom either,trust me as I had the torn up arms to prove it,LOL. Its about 6" of rubber hose with 2 small hose clamps and fits from the return line off the pump to the metal line near the bellhousing above the starter. IF its leaking it will run down the left side of the block nd spray back under the truck while driving. I replaced mine with fuel injection hose and slid some foam fuel line insulation over it then to try and prevent heat breakdown. This is the 3rd time mine has gone bad in 145,000 miles.



Another area for you to check also is your lift pump itself. Remove the rubber primer boot and see if its all wet inside it or around the primer pump on the lift pump. If it is then it is leaking and needs to be replaced also.



Hope those give you some more places to find your problem..... Andy

 

[Joe G.]

He says he replaced the supply and return lines in the first post. If the push button is leaking you don't have to replace the entire lift pump. Only the O-ring. About 50 cents. It can be replaced without removing the lift pump. I haven't heard of a leaking push button causing the truck to run bad.

 

[DDennett]

Yeah I already got that hose, the only ones I haven't done are the flexible sections coming out of the tank. But I will take care of that next weekend along with everything else. Thanks anyway though Andy!

 

[DDennett]

Well I'm still chasing this thing I changed the last of the plastic fuel lines at the tank, the grommet at the fuel supply fitting in the top of the pre-filter, and pressurized the lift pump and stuck it in a bucket of water. The lift pump wasn't leaking but I wound up replacing it anyway due to my own stupidity, but I won't get into that (read I screwed up the seals in the old one). My next step is to go back and recheck the pre filter gasket, thinking maybe it got pinched when I removed the fuel heater, although I would think if that were the case I would see fuel when the truck wasn't running, but you never know. When you guys are replacing the fuel hoses are you putting the new hose over the lip where the old quick disconnect fitting sat? Because I just butted the new hose up against the lip clamped it and all seems to be fine there. I was thinking maybe a bad injector or slipped timing but the starting problem has me leaning toward an air leak and loss of prime, because it starts right up if it hasn't been sitting for more than about 2 hours. Well I just had to get that off my chest since telling all this to the wife is really of no help Any and all ideas will be seriously considered. Thanks guys.

 

[Joe G.]

Take the fuel heater out and see what happens.

 

[DDennett]

Already done, and it was leaking, so I thought that was my problem but no such luck, although it obviously wasn't helping.

 

[DDennett]

Alright I think I have two bad injectors, I loosened the lines with the engine running and #4 & 5 made no difference in engine speed, also those two seemed to spew a lot more fuel with the lines loose than any of the others. I am going to take them all to have tested on Monday and go from there, hopefully this is the problem and I will have this thing back to its old self by the end of the week. Whats the best source for 215 injectors? Any preference as far as having the old ones rebuilt or should I just get new/remans? Do they all need to be matched or can I just replace/have rebuilt the ones that are bad?

thanks

Demian

 

[CTD12V]

Hey Demian, did you ever get your troubles figured out? How hard was the injector test? I am thinking about doing that since I seem to have less power than I used to and so far nothing else has made much difference on the supply/return line issues.



CTD12V

 

[DDennett]

Yeah I figured it out check here:

https://www.turbodieselregistry.com/forums/showthread.php?t=169643

Removing the injectors was not hard, I took them to a local diesel shop to have them pop tested. As far as checking the injectors while the truck was running it was no big deal, you will know when the line is loose enough the engine will start to fall off noticably, it doesn't take much maybe 1/4 to 1/2 a turn, and when you get to the bad injector/s nothing will happen. The procedure is in the fuel system section of the shop manual if you have one.

Hopefully your problem won't turn out like mine has.

Good luck

Demian

 

[EHarvey]

: hammer ,, sorry to but it on this tread but every time i start my truck i have to give it just a little pedal to start, could this be caused by that hose also. if not any ideas? thanks

 

[Joe G.]

That is probably caused by low idle. It should be 800 RPM with the trans in gear and the AC on.

 

[EHarvey]

That is probably caused by low idle. It should be 800 RPM with the trans in gear and the AC on.

thanks for that my idle is 650 just sitting with nothing on and out of gear, with your truck at 800 in gear doesnt it want to go even with brake on. Im gonna try it today. thanks for the help.

 

[Joe G.]

with your truck at 800 in gear doesnt it want to go even with brake on.

Yeah, it does. Holding it with the brake beats dying.