1998 4.3 vortec

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Dougflas
Posts: 96
Joined: Mon Apr 18, 2016 6:10 pm

1998 4.3 vortec

Postby Dougflas » Sun Sep 04, 2016 8:28 am

OK guys, now I could use some help. 1998 Astro Van 4.3. Cranks over, wants to start but won't. I checked fuel pressure at the port in the engine bay on the fuel supply. When turning key on, pressure builds to 60ish and holds at 55psi when turning key off. Put a new distributor rotor and cap on as old ones were corroded. Engine started and ran smoothly. Two days later, won't start. Have spark at output of distributor cap. Vehicle has 107,000 miles original plugs and wires. Plugs are a bear to change on this POS. I am thinking maybe fuel spider? All connectors were reseated. Vehicle has been having this problem for about a month. Won't start. Come back later in the day and it will fire off and run great. This problem now has occurred 4 times in the last week. No codes were set. Any thoughts?
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bohica2xo
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Location: Las Vegas, NV

Re: 1998 4.3 vortec

Postby bohica2xo » Sun Sep 04, 2016 10:37 am

Fuel. Air. Spark. You need all 3

The next time it fails to start, get some fuel in the intake. Pull a vacuum hose & spray flammable brake or carb cleaner in to the intake. Then try again to start it.

You have fuel pressure. That does not mean you have delivery. You have spark when testing, but that may not be present all the time either.

I had a flaky electrical problem drive me nuts - it did just what you described. Under test, the fuel pump ran just fine. Had pressure. Once it was running, it would run for days. But the next time it stopped it would take 20 tries to get it to fire when cranking. The PCM was not firing the injectors. It would run on fuel sprayed in the manifold - then die. It turned out to be the multifunction switch in the steering column...

Do you have a VATS key by any chance?
Dougflas
Posts: 96
Joined: Mon Apr 18, 2016 6:10 pm

Re: 1998 4.3 vortec

Postby Dougflas » Sun Sep 04, 2016 12:24 pm

No VATS. I am sort of leaning toward loss of 12 volts once the ignition switch is in the run position. It seems to occur when there is moisture. Astro vans are hard to work on; last van for me.
GM Tech
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Joined: Fri Apr 22, 2016 7:22 am

Re: 1998 4.3 vortec

Postby GM Tech » Sun Sep 04, 2016 7:28 pm

My 94 Astro has 374,000 on it- I've seen quite a lot of astro issues-- next time it won't start -- have someone crank it while you lay under gas tank and whaaaaap the tank with your fist several times-- this will kick into action a stalled fuel pump- and also let you know that it IS the issue-- I've tried this method dozens of times- and it works most of the time--If van starts, you have just diagnosed the problem- a worn out FP.
Dougflas
Posts: 96
Joined: Mon Apr 18, 2016 6:10 pm

Re: 1998 4.3 vortec

Postby Dougflas » Mon Sep 05, 2016 8:07 am

new problem which may be related. Vehicle starts and runs. The security lamp is lit. I used a generic code reader and it shows no codes. From what I understand, 98 Astro's had 2 kinds of security systems. Mine does not use a special chipped key. Any thoughts?
GM Tech
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Joined: Fri Apr 22, 2016 7:22 am

Re: 1998 4.3 vortec

Postby GM Tech » Mon Sep 05, 2016 9:50 am

It uses Passlock II system- chip is in the tumbler- not the key-- so I usually just bypass them when they act up by buying a GMATTI bypass module off Ebay for $14- instructions are for using when remote starting, but I wire them to be used constantly (permanently ground it- instead of only on remote start request) works great and you'll never see a security light again.. Just search for a bypass module on ebay and the preferred one is a GMATTI.
Last edited by GM Tech on Mon Sep 05, 2016 6:06 pm, edited 1 time in total.
Dougflas
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Re: 1998 4.3 vortec

Postby Dougflas » Mon Sep 05, 2016 5:54 pm

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Mr Bill
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Re: 1998 4.3 vortec

Postby Mr Bill » Thu Sep 08, 2016 3:47 pm

About went off the deep end last year same problem with my 98 GMC. Went to a pick your part and pulled the module from another truck, come back and installed it in mine, did the key on and off reset 3 times it fired right up and been running since. There is a way you can ohm out the module to check to see if it's good, that's what I did, whoever the hero was that come up with this hopefully was fired right after.
“Experience is a hard teacher because she gives the test first, the lesson afterwards". -Vernon Law-
antonioitalia
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Joined: Sun Mar 05, 2017 6:02 am

Re: 1998 4.3 vortec

Postby antonioitalia » Sun Mar 05, 2017 8:23 am

Hi all :)

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