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-   -   1988 Chevy P.U. TBI (http://www.hotrodders.com/forum/1988-chevy-p-u-tbi-3311.html)

Smokeytires 08-27-2002 11:16 AM

1988 Chevy P.U. TBI
 
I've got a problem with a pickup.It will turn over and fire if you spray fuel in the tbi. I've replaced the fuelpump,fuel regulator,oil-fuel sender.I have ran a code check and it doesn't show anything other than 12 code.I've ran test on the map,tps,distributor modual.Would appeciate any help. <img src="confused.gif" border="0">

MHenricks 08-27-2002 11:49 AM

Did you check the fuel pump relay. It should be on the right side under the hood on the fire wall.

Stinkin_V8 08-27-2002 02:31 PM

What I always like to do with those is check the fuel pressure the dumb way. First, turn the key on - the fuel pump should run for 2 seconds and then quit until you engage the starter. You should be able to hear it hum.

There is what's called a Schrader valve on the fuel line up near the TB. There'll be a cap on it about 1/2" diameter and it looks like a tire valve underneath the cap. You're SUPPOSED to hook up a pressure gauge to that, but I find you can open the valve by gently pushing a nail or something into it. If fuel squirts (not trickles) outta there, your pump is fine. If you heard the pump running and still no pressure, check the fuel filter. Only after performing hours of troubleshooting should you then verify that there is fuel in the tank.

Seriously, though - if you check the fuel pressure the dumb way, be very careful.. I would recommend you actually buy a fuel pressure gauge with a Schrader valve attachment.

juxtoposed 08-27-2002 09:55 PM

On this application there is no schrader valve to check fuel pressure. you have to pull the line off of the back of the t-body and put adapters inline to check it. first you need to check for injector pulse at the injector. Get yourself a noid light and poke it into the injector harness and crank it over and see if it flashes. if it does you probably have something wrong with the pump or relay, if it dosen't you probably have something wrong with the module. but if you have spark the module is probably fine. let us know what you find.

Smokeytires 08-28-2002 02:32 AM

I have the truck running. It takes a couple seconds to fire up.My friend told me it was getting harder to start more and more.Yesterday it would start and run ,after I let it set awhile it was real hard to start. After it did it fired up the rest of the day.I checked the module even took it to the parts house and had them check it. Its good.How does the relay work on this system?
Haven't found a node light yet,I'll look more today.Any other advice would be nice. <img src="confused.gif" border="0">

KULTULZ 08-28-2002 03:50 AM

The fuel pump relay actually supplies voltage (12V) to the pump. It sould be located on the passenger side firewall (outer) under a large plastic shield.

A universal noid light is available from Lisle Tools. It will work on most applications.

Remove the distributor cap and see if there is any corrosion (green gunk) around the module leads. Replacement of the module and/or pickup is fairly easy. The lead)s) are still available for service. Check to see if the injector harness(es) have their insulation rubbed through at any point from the air cleaner adaptor.

Did you by any chance have to remove the engine elecrical control harness at any point?

Smokeytires 08-28-2002 06:03 PM

Does anyone know if there should be pressure in the gas line after the engine is shut down.It seems to bleed down when shut off.It doesn't have a test valve so I was wondering about this.It seems to be running at this point.

juxtoposed 08-28-2002 10:03 PM

yes it should hold pressure for a little while after you turn it off. I would say that the noid light is probably not needed in your case because it is running, so it will have pulse. I thought this was a no start situation from your earlier posts. Hard starts and poor driveability could be as simple as needing a tune up.

juxtoposed 08-28-2002 10:04 PM

I just reread your posts and you didn"t mention changing the fuel filter. you might check that.

KULTULZ 08-29-2002 12:57 AM

[quote]Does anyone know if there should be pressure in the gas line after the engine is shut down. It seems to bleed down when shut off.<hr></blockquote>

It will not hold pressure as it is a low pressure (9-14lbs) TBI system.

Changing the filter is a good suggestion. The last one I pulled off was almost completely blocked.

Smokeytires 08-29-2002 02:35 AM

Thanks for all the help guys.The inline fuel filter was the first thing I changed.It has had an earlier tuneup.I'll go back and check it out.It has new wires cap and rotor.He has the exhaust off from the muffler back.Hes doesn't seem to fix other problem areas.I thought maybe this may be throwing off the o2 sensor?S\T

Copper Top 10-17-2002 08:13 PM

it is entirely possible that it's your pcm giving you grief, once it starts to give you problems it just keeps adding to them.they are easy to take out so it might not be a bad idea to have it tested.

roys63 10-18-2002 12:54 AM

This may be a injector problem if this has high miles?Use a timing light to watch the spray and you must check your fuel press you may have the wrong or a bad pump

[ October 19, 2002: Message edited by: roys63 ]</p>

tm454 10-28-2002 04:39 AM

Smokey, what happend? Did the fuel filter fix it or was the fuel pump bad or the relay? <img src="confused.gif" border="0">


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