Engine/Transmission (1994 - 1998) hard start really hard start

[Swineheart]

I had a new fuel heater put on about 5000 miles ago and it started great in cold weather. but lately it starts so hard you have to hold the petal to the floor and crank the thing almost dead. I noticed the back of the p7100 is wet I can't find any other leaks. Is that fuel heater even needed I' ve been told it's only for emissions?

 

[surfbeetle]

Do a search and you'll find a ton of info. Also, look for Joe G. 's write up on the 12 valve fuel system. His email is -- email address removed --. Obviously, if your pump is wet, that is not a good sign, you'll need to see if that is a leak that is causing the system to lose its prime. The most common thing is the fuel lines that run from the frame by the trans up to the engine. They crack and cause this as well.

 

[WilsonF]

If you are from Alaska it MIGHT help but I think some from there have removed it with no ill effects. I think your starting problem is air get into the fuel system. I have Joe G's write up it covers it very well. You should get it.

Floyd

 

[EKlem]

Does it get harder to start the longer you leave it? If so, that is often the sign of an air leak. Your fuel preheater is a likely culprit but if the back of your IP is wet, I would start looking there. If your return line leaks fuel, you will have trouble starting.

As far as ditching the fuel heater goes, I would be hesitant to in a really cold climate. The heater's purpose is to keep the fuel just warm enough so that it will not plug your fuel filter when it is really cold. I still have the heater in my truck but the relay for it is unplugged so that it won't burn out. If my fuel pressure starts dropping, I can plug it back in.

 

[Swineheart]

Yes the longer you leave it you need to pump the primer to get it started and it still starts hard.

 

[PRohr]

How old is the LP? How much fuel pressure do you have? I was havinga hard start like that and it turned out to be a bad LP. I went through 4 of those things in 3 years... . put the FASS on and have never looked back. Two of those 4 were from Cummins too.

 

[Joe G.]

If you are from Alaska it MIGHT help

A guy on another forum who goes by YKDave has removed his fuel heater and some others. All of them start ok in 30 below weather. His opinion of the fuel heater is that it is a hunk of junk. YK stands for where he lives: Yellow Knife.

 

[Swineheart]

How old is the LP? How much fuel pressure do you have? I has waving a hard start like that and it turned out to be a bad LP. I went through 4 of those things in 3 years... . put the FASS on and have never looked back. Two of those 4 were from Cummins too.

I don't know how old it's pretty dirty looking and I have 218000 miles on the truck. I am going to check the fuel pressure tomorrow. I have a FASS 95/150 off my 2002 ctd I don't know if I could wire it up to my truck?

 

[Bob V]

When it starts does it run good right after it starts? If it runs rough right after is starts it is most likely air in the system. If it idles fine, try REPLACING the fuel shut down relay (not the solenoid). If you try to test the relay with a test light/volt meter you can get a false reading. The contacts in the relay can allow enough current to light the test light/volt meter but not enough to pull in the solenoid.

 

[DonFitzwater]

Eliminate the shutdown solenoid first since thats easy. Make good and sure your return lines are in good shape and no holes have been rubbed in the metal lines near the fire wall.

 

[Swineheart]

I have found 2 leaks in the fuel lines I replaced them both all the way back to the fuel tank and put a new fuel filter in. and plumbed in a fuel pressure gauge I had sitting around. I have 12lbs of max pressure I think I have air in the regulator when I shut it off in 2 minutes the pressure drops to zero. The truck does start easier but still need to use some pedal.

 

[Joe G.]

Email me at -- email address removed -- for my 12 valve fuel supply system write up, how it works and how to fix it. I think you either have a burned up fuel heater or a bad grommet in the connection to the fuel heater/pre-filter assembly if it continues to be hard to start. There are other possibilities that are covered in the write up.

If it starts ok now and tomorrow except for pushing the pedal a little, then you are good to go. It's NOT a problem to have to press the pedal. These relics are mechanical, no computer to help them start. If you want it to start with no pedal then set the idle up a little bit.

 

[PRohr]

The fuel pressure is way low as well. . 12 psi max is not enough. IIRC stock should be 17psi at idle.

 

[Missouri Mule]

!2 valves with the P7100 need to be 20 psi minimum on the supply side of the filter. Revved in neutral should go to at least 30 psi.

While your taking a fuel pressure test it is a good idea to sqeeze the return line to rule out the overflow valve. ( While squeezing if pressure goes up it is the overflow valve, if it stays the same or goes up slowly it is the lift pump. )

 

[Joe G.]

!2 valves with the P7100 need to be 20 psi minimum on the supply side of the filter. Revved in neutral should go to at least 30 psi.
While your taking a fuel pressure test it is a good idea to sqeeze the return line to rule out the overflow valve. ( While squeezing if pressure goes up it is the overflow valve, if it stays the same or goes up slowly it is the lift pump. )

Don't jump to conclusions that it's the lift pump. MUCH more likely that it's an air leak. It's easy to check out the lift pump. Use a bucket of fuel. Take the short curved hose off that is between the pre-filter and the lift pump. Connect a hose from the bucket to the lift pump. It may be a little hard to start until the air is out of the hose to the bucket, but after that if it starts ok the lift pump is good.