Anybody know there way around a mid 90's silverado?

[Eikon]

I'm thinking of buying an old used truck on craigslist.. something to run to home depot with, haul mulch or car parts or whatever...

I found a local ad.. http://akroncanton.craigslist.org/cto/2464484080.html

Seems like a nice truck for $1250 or less.. But, if it doesn't run, it does me no good.


Can anyone suggest what might be the problem with this thing? That ad says engine and trans are both pretty new (rebuilt) and if it runs good for 30 second at startup, then the internals should be good. Must be a sensor or fuel issue or something.. Any ideas? I asked it would run so that I could drive it home and he said yes.... but would only get like 5 mpg.. which is another interesting clue.

Any ideas?

[Eikon]

Seems to me like it would be something with open loop / closed loop issues.. Like at "cold temps" the ECU controls the sensors, but then when it reaches normal operating temps and is supposed to run on it's own, then it struggles. . Temp sensor would seem like a possibility, but he says he replaced it already.

[Razi]

Hmm, a lot of the stuff I would've suspected have been replaced already..

I would check the fuel pressure and injectors.

Some searching on Google shows that someone had a problem with a coil in the distributor, but I would think that would make the car run badly all the time, not only after it warmed up for 30 seconds...

[Jesda]

GMT400s are awesome. Big, boxy, and they ride like Fleetwoods.

I'm stumped on that one. Typical T400 issues are water pumps and rust at the bottom toward the back of the cab.

[Pento240sx]

Or this:
http://mansfield.craigslist.org/cto/2447671240.html

[Oatmealman]

something in the fuel system definatley.The fact that it runs but only runs for 30 seconds or so and would get bad gas mileage are huge tips.I'd check fuel pressure,spent 7 bucks and put a new fuel filter on it(its a couple of bucks you might loose),I always do a compression check on vehicles im buying,hell most the time if I've got the tools available ill do a leak down test.


here's the things i always check on a used vehicle im buying
compression
leak down(if possible)
fuel pressure (again if possible)
Smoke(i love when smoke comes,means i can beat em way down on price)
listen,feel and watch are the biggest one.I've known guys who can diagnose a vehicle by this.

There isn't much to those old things.and parts are dirt cheap.If it's the vortec engine a slight drop in fuel pressure means the engine will run but for a short time and will get horrible gas mileage,and by slight drop i mean like 3-5 psi.

also look at the fpr,check the fuel pressure with the vehicle running.

[sx moneypit]

I would put money on it being a fuel pump.I work on a ton of those trucks.The fuel pressure is only 9-13 lbs on the TBI injection.Any drop in the pressure will affect the performance.

[darens13]

did he adjust the tps for the correct voltage when he installed it?

that looks like a pretty good deal for that pickup. i have been driving my '90 half ton chevy since my 240 is down. awesome rig and parts are easy to find and cheap.

[Eikon]

Not sure about the tps voltage. He did have a Haynes manual in the truck and a bunch of tools in the back, so it seemed like he was a decent mechanic.

So, yeah... I went to look at the truck yesterday. I didn't buy it on the spot or even make him an offer... I told him I'd consider it and get back to him.

His ad says it has some rust on the cab corners... not really true.. they are completely gone. Just a big rusty mess. The rest of the truck isn't bad for rust.. one hole on a front fender and some bubbling and surface rust around the others.

He started the motor and it sounded good.. though it seemed like it had a high idle to me. After it got warmed up (45 second to a minute it seemed), it dropped revs a little bit (maybe 100 rpm at most), but still seemed to idle smooth. I didn't hear any tapping, knocking or anything.. seemed pretty smooth. I was expecting an erratic or choppy idle, but it was fine. So we decided to go for a quick "test drive". The trans shifts as smooth as butter.. The motor.. not so good.

If you let it run itself out on idle, it runs fine, but as soon as you touch the gas it quits and wants to die. I can't tell if its getting too much gas or not enough, but my guess is too much gas? When you let off the gas pedal, then it resumes running at idle.


So far my guesses (from other advisers or myself) for the repair would be the ignition coil, a fuel filter, or perhaps a vacuum leak.

Anybody have opinions on the issue?


Again, the rust was worse than I thought on the can corners and the clear-coat was peeling pretty bad, but I don't care that much about those things... I just want the utility of a truck.. for cheap.. so I know I'm not going to get anything pretty.

[elwesso]

Unless the injectors are leaking I'd say it would be a lean condition.. Without a fuel pressure test you're just guessing.. I know on the old Q's with bad fuel pumps they will idle and run around town OK but will want to stall and run outta breath at higher RPM..

If it was running rich enough to make that happen there would be black smoke coming from the tail pipe.. Probably pretty noticeable when driving since those should have the pipes coming out the side.

My suggestion would be to take a fuel pressure reading after the fuel filter and see what it comes up with.. Might get lucky and have the fuel filter plugged?

[MinisterofDOOM]

GMT400s are awesome. Big, boxy, and they ride like Fleetwoods.

And they have one of the worst dashboards in the history of the automobile. Maybe even THE worst.
And those climate controls.

[Rev_D21]

I happen to like that era of GM trucks. At 21 years old there could be a good sized vacuum leak causing problems. Those hoses only last so long.

[Jesda]

GMT400s are awesome. Big, boxy, and they ride like Fleetwoods.

And they have one of the worst dashboards in the history of the automobile. Maybe even THE worst.
And those climate controls.

I love them, especially those sliding half moons!

[Eikon]

I didn't buy the truck. I would have been happy to work on the motor, but in the end I decided it was just too rusty. For $2500 I can get truck with little to no rust and a running motor and I'll be much happier about it.