Engine/Transmission (1994 - 1998) Hard Starting after sitting a few days

[LFalconer]

All,



My son's truck with 147K starts and runs fine when it sits say a few hours, or overnite.



However - if let sit for 3-7 days - then it is hard to start, kind of like it has lost the prime, once it runs for say 30 seconds and "clears" then it is ok again.



Any thoughts as to what this might be?



Thanks,



Luke

 

[ttbird]

Yes Luke, it's a familiar problem with 12 valves. The rubber fuel lines go bad or the fuel heater burns up and leaks. There are alot of posts concerning this. Search forum under 12 valves and you'll have your fill of reading. You should find all the info that you need. If not, post again and I'll try to touch on most areas with problems for you.
Tom

 

[LFalconer]

Tom, Thanks for the pointer - I'll search and see what I find.



I suspected the fuel lines, and we looked them over, no leaks apparent.



Luke

 

[hsmith]

If they are original hoses, replace them for sure. Leaks there are hard to see as it will be very slight. Also, discard the pre-heater also. It can leak at the connector, causing a loss of prime, and also be hard to see. It is not needed anyway.

Smitty

 

[Joe G.]

Email me at -- email address removed -- for my write up on the fuel supply system, how it works and how to fix it.

 

[fox]

A common find is the return line at the rear of the head. Seldom does it leak fuel. Replace the hose.

 

[Gene Arnold]

Ditto on what they said. Been there, done that!



Gene

 

[Howard Durand]

I just went through a hose replacement process and have a few pointers. First, don't replace it with normal fuel rated rubber hose. It won't last as long as the original hose.

Foster Truck sells a kit of marine grade hose for this application. It is good hose but is much harder walled than the rubber hose and is a little more difficult to get it to push over the metal lines. The location of the hoses doesn't help much either.

I found that if I smear the pointed end of a spud bar with some Sil Glide lubricant, available at NAPA, and push the bar into the end of the hose, it will expand enough to make it easier to slip over the metal line. The harder hose seems to hold the expansion long enough to allow you to get it in place.



Foster Truck's kit includes 2' lengths of both 5/16" and 3/8" hose which is what is required by most of these trucks.

Unfortunately, my 94 is different, It has a mixed up affair of two 5/16" steel lines coming from the fuel tank. They both have to make up, through the hoses, to the two steel lines at the engine. The line to the overflow valve is 5/16" but the one to the pre-filter/fuel pump assembly is 3/8". I had to use the 3/8" hose there but it would not clamp down tight enough on the 5/16" line to the tank to prevent an air leak. That has been fixed by attaching a 3/8" barb and compression fitting to the 5/16" line.



Sorry about the long post but maybe this will help someone avoid some trouble.

 

[The patriot]

Ditto on what they said, however mine was doing the same thing. I went through all the usual suspects, and it turned out to be the lift pump.

There are acceptions to the rule... ...

 

[Joe G.]

Has anyone taken one of these bad lift pumps apart to see what is wrong with it? I would like to know what failed.

 

[The patriot]

I didnt take mine apart, because I dont know where to get replacement parts for it.

I didnt think it mattered if it couldnt be rectified.



My truck would start up and run, but it was a little slow on the starting, and it was down a bit on the power when started.

I drain my filter regularly, and when I was draining it while it was running, it stalled out. Right away I knew this wasnt what it always did.

 

[Joe G.]

If someone would take one of the replaced lift pumps apart maybe we could see what goes wrong with them. If a spring or a check valve breaks then I would think it would quit. Maybe it won't quit if that happens. If the springs and check valves are ok, then maybe you had a bad O-ring so there was a small air leak. The filter symptom you describe is almost always an air leak. Maybe the piston was all scuffed up. You also may have had a small leak in the fitting that has the fiber washer in it that fastens the input steel fuel line to the fuel heater/pre-filter assembly. You had to take that off and put it back to replace the lift pump. The short curved hose between the pre-filter and the lift pump may have been leaking a little air that was fixed by reseating it when the lift pump was replaced. Anyway, I would like to know what fails when one of these simple lift pumps dies.

 

[GOlsen]

I'm going to be replacing my lift pump this weekend. I'll take it apart and see if I can not anything (I'll also take pictures).

 

[Joe G.]

Is your lift pump dead? Or is it performing poorly? What are your symptoms?