94 XLT not turning over

[rayder34]

For the past 6 months about once a month I have had trouble getting started. After about 30 tries it has so far always started... until this AM. Won't kick over for the life of me. I drive it daily and start it multiple times a day with no problems.
Truck has 190k miles on it.
So far I have changed spark pugs and wires, air filter, pcv valve. Added fuel injector cleaner to gas.
Not sure what else to do. I have yet to take it in because it happens so infrequently (but always at worst times) it drives me nuts

It cranks likes it wants to turn but just has trouble doing it.

any suggestions?

 

[TPLYNCH]

When you turn the key to "On", wait before turning all the way to start. You should hear a whine from the Fuel Pump for a second or two. If you don't hear that whine, then either the relay in the black box under the hood could be bad, or worst case the Fuel Pump itself is bad. If you search for Fuel Pump and Relay, you should find several threads with diagnostics/fixes etc.

If you hear the fuel pump whine, check via the schrader(?) valve on the fuel rail that gas is in fact making it to the injectors. If you do have fuel, then it's an electrical problem... Coil Packs? Camshaft Position Sensor?

Good luck.

 

[mabulok]

When you say "cranks like it wants to turn", do you mean it cranks slowly? Or does the starter turn over normally but take longer to start the engine up?

 

[DHB]

94 xlt

check your positive battery cable, could be corroded inside not letting current get through. connect booster cable from positive battery post to starter , should start, if so replace battery cable should fix problem

 

[rayder34]

Thanks guys....
I got it started after letting it sit for a while- I listen for the "whine" and hear it intermittently- when I hear it it starts. I changed the relay and it didn't help. Does that mean it is most likely fuel pump?
Mabulok-It does not crank slowly, sounds normal but nevers starts
DHB - I will try your suggestion.
I am trying to avoid fuel pump replacement for obvious reasons

 

[MrShorty]

I changed the relay and it didn't help. Does that mean it is most likely fuel pump?

Not "most likely." There are several other components in the fuel pump circuit that could cause an intermittent failure, including:
EEC relay
EEC-IV computer
inertia switch
fuel pump ground
fuse/fusible link
ground connection
and several feet of wiring and associated connectors.
My advice:
1) Get a wiring diagram to see what goes where.
2) Run EEC-IV KOEO self-test. May be some useful information in the trouble codes that come up
3) When it fails, start probing the circuit with a DVOM/test light until you locate the failure. It's tedious, and the fact that the fault is intermittent will make it that much more difficult to find, but that's the best way to find the real fault. I'm with you, I wouldn't want to replace the fuel pump if the fuel pump wasn't at fault.

 

[shifty1]

I was having the same problem, it would turn over strong but would not start. When it would start you could hear the Fuel Pump, but when it wouldnt start, you couldnt hear the whine. It turned out to be the EEC Relay. One of the 5 prongs was twisted so it was not making a full time connection. It started as a very intermittent problem (die while driving every 3-4 weeks) but progressed to every few km's. Went on for 9 months and at least 2 trips to a garage for diagnosis (wasted time and $).
Try playing with the relays, maybe switch a few(they are all the same), see if that helps.
When its stalling, pull a plug and check for spark. I believe that the FP will not prime if there is no spark.
Thats how I changed from focusing on fuel problems. Luckily I found the problem on Friday, I had an appt to change the FP at a buddies garage on monday. I am much happier with a $7 relay that fixed the problem than a $230 FP that wouldnt have fixed anything.

Good luck

 

[rayder34]

I have to revisit this thread since it is happening again
Yesterday I stopped for gas and it would not start. After changing relays with no success I disconnected the fuel shut off plug beneath the passenger carpet behind the firewall. The reset button was not tripped. I plugged it back in and it started right up.
Coincedence? or could this be a sign of problem?

BTW- I have never had a problem with it shut down on me while driving. only not starting up.

 

[MrShorty]

Could just be a bad connection at the inertia switch, or unplugging the inertia switch and then plugging it back in was just coincedence. As suggested before, get a wiring diagram and go through the fuel pump circuit and see if you can find anything. The fact that the fault is intermittent is going to make it that much more difficult to find.

 

[Opera House]

At 190K, it could be the fuel pump. This can be difficult to diagnose without adding a monitoring system. This monitor can be as simple as a small lamp in the cab wired to the pump wire at the tank. Remember that when the engine stops for any reason, the computer will turn off the fuel pump relay. Try to restart and see if the lamp comes on for 3-5 seconds. If it fails to do this, also have a switch to power the pump/lamp directly from the battery. If the switch powers it, you know at least you have an electrical problem. I have a little box with 4 LEDs just for this purpose to monitor various power points. Unless you wire something in, you will never figure this out.