Yet another "No Start" problem

[mohawkman]

Hello eveyone, new guy here and first-time poster. Lemme just say that I know virtually nothing about vehicles, lol. I have a friend/co-worker that does the mechanic work on my truck, so any replies that are "too technical" I may not comprehend and, therefore, will be unable to give an intelligent response.

Anyway, my mechanic is bumfuzzled by this and I was hoping some of you might have a suggestion as to what else we can try.

I have a 94 K-1500 with a 5.7 litre fuel injected throttle body that I can't keep running. It won't start on it's own, but if I pour a little gas down the throttle body it'll hit and, after a few chugs and spits, it runs fine....as long as I keep a foot on the gas pedal. As soon as I lift my foot, it dies. I managed to get the truck back to work by running stop signs and driving the tar out of it, but it died as soon as I lifted my foot again.

Anyway, my mechanic changed the fuel pump, fuel filter and something he called a TPS switch or sensor on the passenger side of the throttle body. (Another guy at work with a similar model truck was having the same problem and he said this switch or sensor cleared his problem up). He reset the idle on it and I drove it around the block. I came to a dead stop at the stop signs and lifted my foot off the gas pedal and the truck sat and idled perfectly....didn't even offer to quit on me. Several hours later, I got in it to drive home and it fired right up on the first crank. I drove it home without any incident and parked it in the driveway. The next day (yesterday) I went out to get in it to go to town and it was the same problem all over again....wouldn't start on it's own without pouring a little gas in the throttle body and dying as soon as I lifted my foot off the gas pedal.

I was browsing through these forums yesterday and saw a few suggestions, but nothing I can personally do myself aside from disconneting the battery for awhile to let the computer reset (which I'm getting ready to go do in a minute).

If anyone has any other suggestions that we might try, I would surely appreciate it. This is my only vehicle and I obviously need it to get around.

Thanks in advance.

[leolkfrm]

check the EGR it may be sticking open, ecm temp switch may be going bad, have you scanned it yet?

[mohawkman]

Thanks. I'm going to assume by "scanning" it you mean taking it to a dealer and putting it on their computer? No, haven't done that yet.

[Case 7230]

The EGR valve is a good possibility however before you throw any more parts at it I would check for any stored error codes. You can do that with just a paperclip. Do a search of this forum for something like "Pulling Codes" or "Reading Codes" for instructions. It may also be useful to check on the fuel pressure.
Good luck with it.

[leolkfrm]

other people besides dealers can scan and it will be cheaper. Good local people will have mac or snapon tools that work well

[mohawkman]

Thanks again to all. Yeah, in my case at least, cheaper is better.

[crabtruck]

Welcome to the forum mohawkman.
Since it's a 94 you can read the codes with a small paperclip.
Bend it into a triangle and look through it at the computer.
OK, kidding, but the real way is easy too.

There is a plug attatched to the lower left side of dash near hood release,
you can see it from seat.



On that connector A&B are the two on top, right corner.
The letters are embossed on the plastic. That's an OBD-I type.
For OBD-I a paperclip is about as good as a scanner.
Codes are read by shorting the pin holes with key on, engine off.
( This means engine codes, not antilock brake codes, diff pins. )

Codes (if any) will flash the check lite for each code a certain number of times.
When done, it will repeat them all again. Write down the codes.
A code of 1-2 (12) is "no codes stored"

You could ask local parts place for free scan, some do it.
Try to not disconnect battery or random fuses before getting a read
because that can reset codes. Reading them will not erase them.
That's easiest done by pulling the "ECM-B" fuse for 30secs.

Your truck is in the conversion year for OBD I & II, (system for codes)
you can check which you have on the upper right corner of radiator emmissions label.
You probably have OBD I and the connector would look like this picture.
The OBD-II type has just slightly different shape, so read label.

You pull the codes and we can help with translating them.

[mohawkman]

Well, I went out and disconnected the negative side of the battery and let it sit for about an hour. Went back out, reconnected the battery and got in, turned the key and it started right up on the first crank and idled just fine. Weird huh?

Anybody know what would make it do that? Anything else I should have checked in case this is an intermittant problem?

Thanks again.

[mohawkman]

Thanks for the info. I'm gonna do a copy/paste of this thread and take the print-out to my mechanic tomorrow. Really appreciate all the help and info from everyone here, you guys rock!

[mohawkman]

Ah, darn, I just disconnected/reconnected battery before I read your reply. But if the problem itself is still there and just acting up randomly, the codes will come back, right?