Engine/Transmission (1994 - 1998) another hard start 12v question....

[pwerwagn]

Ok, last sunday I got up, went out and got in the truck. it usually starts instantly. It cranked a bit, then fired. I thought, oh, no biggie prolly. well, the rest of the day it started fine. then monday morning I get up, same thing. same throughout the week. so I think, maybe I got bad gas or water in the seperator. so, I drain the water from the sep. I couldnt get it to start back up!!! I pushed the primer 6,938 times (kidding) and never could get anything to happen. finally, after holding the pedal to the floor, it would start but run rough.

I read Joe G's info about the fuel heater, just removing the center section. I also messed with the OF valve, tightned it up. I did notice that the OF valve spring seems to be kinda weak.

I think its not the fuel sol, because it starts fine if I put some throttle in it. also, prolly not a relay problem I assume... .



any suggestions?



thanks,

Jeff

 

[Johnstra]

If you search for "low fuel pressure" or "air leak" you'll find several more things you can try to isolate the problem. Sounds like an air leak. It's usually the in/out fuel lines, 1/2" line between lift pump and fuel heater, or something on the pre-filter/fuel heater housing. Did you clean your pre-filter when you removed the fuel heater?

-john

 

[JFaughn]

fuel presure test first then look for other problums.

 

[pwerwagn]

I searched and read for hours on end about low pressure, hard starting, air leaks, etc. Im gonna try the fuel filter first, and clean the strainer and inspect the pre-heater. if that fails, Im gonna replace the lines. All that needs to be done anyway, so now is a good time to start. If that fails, I guess I'll pressure test it.

--thanks,

Jeff

 

[Joe G.]

I think its not the fuel sol, because it starts fine if I put some throttle in it.

Your idle is too low. It should be at least 750 RPM with the AC on. 800 is better.

 

[pwerwagn]

Actually, the idle is right at about 775 with the A/c on. (i hate the way our tach's are graduated... . not in 100rpm increments).



I think it may be coincidental that when I give it fuel it starts. last night I was messing with it. With the key on, the fuel soleniod is down, I have to manually pull it up. I go start it, and sometimes it starts good, other times not. I think the relay is prolly going south, or maybe the pull coil on the solenoid.



--Jeff

 

[Joe G.]

The solenoid pulls up if the key is in start. It is held up if the key is in run, but that won't pull it up. The relay is simple to change so might as well do that. The pull coil on the fuel solenoid seldom fails. It may be a problem with the blue wire on the positive post of the battery. It is prone to corrosion and is a fusable link. Might try cleaning the blue wire connection to the battery post. You might also check to see if the solenoid boot is a mess and jamming up the works some times.

 

[pwerwagn]

Oh, Well the solenoid is up after the truck starts. I was thinking that it pulled up when the key was turned to the run position. So since it doesnt pull up until you actually crank it, that must not be my problem.



Back to square one... ... .



--Jeff

 

[Johnstra]

Can you rig up a fuel pressure guage? That's what I'd do next.

-john

 

[Joe G.]

What John said. If you have low fuel pressure then you probably have an air leak. Remember you can't see an air leak so looking at hoses and whatever ain't gonna find it.

 

[Andy Redmond]

Next time it doesn't fire right off, leave the key on and raise the hood is the solenoid arm up? If not, look the to relay or wiring as Joe suggested.



I changed the relay for the first time on my ride last week. It would crank a little more than normal then one day, just cranked over, but no fire. I pulled in a spare relay and its fired the first time, every time since.



Otherwise you are on the right track, you might also ck. out issue 49. I typed a few pages sure to put you to sleep.



Good luck,

Andy

 

[pwerwagn]

Thanks guys.

It seems to be getting better, so I hoped maybe I had got a bad batch of fuel, but this morning it came back again.

I am going to pressure test it next. If that aint the prob, then I'll go ahead and put a new relay on.

I read 49, andy. Didnt put me to sleep at all!



thanks for the help guys,

Jeff

 

[EBottema]

My dads truck has been having a similar problem.



We checked the return lines and no leaks.



The truck only starts if you slightly tap the pedel. Starts up and runs fine? I have no idea on this one... .

 

[ELake]

same deal with mine... I raised the idle to around 900 and it starts a lot faster, still not as fast as it should. I stretched the overflow spring and put a new fuel filter on too. Also checked the lines leaks... I got never did get around to cleaning the prefilter thats next on my list. . I suspect bad things or maybe even a lift pump if I can jimmy a gauge on there somehow.....

 

[pwerwagn]

OK, 2 more discovery's to add to the list:



For starters (hopefully this is the problem):

I degreased around the pump really good. After running it for a few days, there is a diesel residue (fairly heavy) around the OF valve. so maybe I have a leak there..... so I pulled the little bolt that holds the spring in out, and the spring is in pieces!!!!???? the truck still runs great once it starts... could that be the probeem?



On another note, I also drained the water seperator on the filter. I only drained about an ounce. The truck wouldnt start!!!! I tried to prime the pump with the manual prime, and nothing, just air in the primer. I cycled the key on and off dozens of times to try to get the LP to build pressure, nothing. Finally, with the foot to the floor and a lot of cranking, it fired.

Is that common?? Mine also takes a LOOONG time to prime when I change a fuel filter... .



--Jeff

 

[Joe G.]

The OF valve is definitly a problem, but that won't prevent you from pumping the filter full of fuel. An air leak will. Mine was that way with a bad fuel heater. The fuel heater is easy to check. Two tools are needed; a 17mm socket and an 8mm allen wrench. Remove the bowl from the bottom of the pre-filter. The fuel heater is the black hockey puck looking thing above the pre-filter. Remove the big screw that holds it in place with the allen wrench. Unplug the fuel heater and put it and the screw that holds it in on your work bench. The pre-filter will fasten where the fuel heater was with no problem. Use one of the gaskets to install the pre-filter. See how everything works with the fuel heater out.

 

[pwerwagn]

Thanks Joe. I had checked out your pics of that idea in your readers rigs. Im gonna try that first and see what happens.



thanks,

Jeff

 

[pwerwagn]

Fixed!!!!

Well, I removed the OF valve, it seemed to have a film of diesel on it, and sure enough it was leaking.

no more hard start problems!!!!

thanks for all the help and suggestions,

Jeff