[sxfx]

Hi guys Im new to the board just recently acquired a Astro van and have run up with some issues. It is a 1988 4.3 V6 with only 63k Miles on it.

I have so far replaced the TBI gasket, fuel filter, and map sensor. Here is the issue I am having. Im thinking it might be my fuel pump but Il let you guys be the judges.

Basically when everything is hooked up properly the car starts runs for a split second then shuts off. But if I unhook the vacuum hose from the map sensor the car turns over and idles for about 5 to 10 minutes before dying out. Of course if I put it in gear at that point it will die right away too.

Also when I turn it on and let it idle with the vacuum from the map sensor unhooked when I hit the gas pedal quickly it tries to bog down but if I press on the gas pedal gradually it will raise in rpm all the way till red line.

Any suggestions are helpful, thank ahead of time.
Mike

 

[sxfx]

Just wanted to say.

http://www.2carpros.com/forum/1987-chev ... 05183.html

I am having the exact same problem as the guy on that board.

 

[Matrixx]

Hi sxfx
Welcome to the board. I saw this post when you first put it up. I was hoping someone would chime in that had this year (I don't). Having said that, I have worked on a few and owned an 88 cargo van but on duel fuel (Gas/Propane). Having that little miles on your van is a good thing one way, but can be not so good in another, it really depends on how it was maintained while in storage.

Either way, you will need to break this broad problem down into 3-parts, Fuel-Air-Spark.
-Fuel: Correct Pressure (9-13 PSI) - Fuel Regulation
-Air: No Vacuum Leaks (Cracked or Broken Vac Lines) - Good PCV Valve
-Spark: Strong Blue spark from all points leading to the plug - Good Plugs.

These are Basic starting points to help you narrow down the area that is causing this problem for you, and the way I would do it myself. Please keep us updated, Thanks.

PS: Was this problem present before or after you worked on the van? Thanks.

 

[sxfx]

Hi, back with an update.

So I I checked all my ignition components made sure timing was set correctly my cap and rotors were in good working condition replaced my coil, fuel pump.

Pretty much 80% of Ignition and fuel components are working just fine and are pretty much brand new. Iv been tinkering with everything for the last two weeks.

When whoa and behold I come across the thread that the link I posted to above.

Today how ever one person that is having similar issues as me and the original poster of that thread mentioned above posts this.

" Van computer chip PROM programmed to shut down fuel injectors after 20 years from manufact. date and show no trouble code 51. Thank GM Corp. Electrical Engineer checked old PROM chip data."

Just curious is any one else here with a 1988 Astro that can confirm any of the simillar symptoms.

Thanks.

 

[astro355]

I thought throttle body setups had fuel pressures 35 psi and higher. :?:

OP, please try this. When you unplug the vacuum hose from the map sensor, cover the hose with your thumb. What does the engine do then?

 

[Matrixx]

Hi astro355
I checked the year (88-V6 4.3) for fuel pressure and it states 9-13 PSI. If their is anything else that you have that states differently, please let us know. Like I said earlier, I don't have this year, and I want to make sure we give accurate information to the people who ask. That's what All Data States though. Thanks.

 

[astro355]

No, you're right. I just looked it up. For the TBI, its listed at 9-13 psi, CPI is 55-61 psi. I have never heard of a fuel injection setup running that low of a fuel pressure. :shrug: Learn something everyday.

 

[astro355]

Now I remember why I thought that. When I did the V8 swap in my van, I had to replace the fuel pump because the pressure was too high for the carb I put on it.

 

[Matrixx]

Hi stro355
I thought it was a bit low as well, that's why I rechecked after you mentioned it. Both Auto Zone and All Data states 9-13 PSI. Still think it's a bit low for an Injected system, usually you see that type of pressure on Mechanical fuel pumps.

Yes we do learn something new everyday for sure, thanks for the response and I apologize to the OP for side tracking this thread. Just wanted to make sure the information was correct.

 

[astro355]

OP, please try this. When you unplug the vacuum hose from the map sensor, cover the hose with your thumb. What does the engine do then?

 

[sxfx]

Ok when I unplug the map sensor and cover the vacuum port on the TBI up it still idles, I haven't thought about covering the port from the map sensor but that shouldn't make a difference since the map is looking for input from the port on the TBI right.

For some reason it just seems the minute it gets inpute from a vac source the car starts going bonkers.

I just don't understand it heh its weird.

Newest and latest is that I don't know how but I got it to idle with the map sensor hooked up but it buckles and jumps wildly and wants to die heh.

Im going to do a compression test today and see whats going on, and I haven't checked fuel pressure yet I will do all that this weekend.

Anyone know can I pick up a fuel pressure tester from autozone for a TBI unit and should I hook it up inline with my fuel filter or at the TBI.

Right now I'm leaning towards bad fuel pressure regulator or bad fuel pump.

 

[astro355]

Ok when I unplug the map sensor and cover the vacuum port on the TBI up it still idles, I haven't thought about covering the port from the map sensor but that shouldn't make a difference since the map is looking for input from the port on the TBI right.

For some reason it just seems the minute it gets inpute from a vac source the car starts going bonkers.

I just don't understand it heh its weird.

Newest and latest is that I don't know how but I got it to idle with the map sensor hooked up but it buckles and jumps wildly and wants to die heh.

Im going to do a compression test today and see whats going on, and I haven't checked fuel pressure yet I will do all that this weekend.

Anyone know can I pick up a fuel pressure tester from autozone for a TBI unit and should I hook it up inline with my fuel filter or at the TBI.

Right now I'm leaning towards bad fuel pressure regulator or bad fuel pump.

The reason I wanted you to cover up the end of the vacuum line that plugs into the MAP sensor is to determine if its a problem with the MAP sensor or if the air/fuel mixture is too rich. Unplugging any vacuum line would introduce more air into the engine. Also, if the vacuum line is cracked, this is a good way to tell. I don't want you to cover up the port on the MAP sensor, I would you to cover the end of the vacuum line while the other end is still plugged into the TB. So please, unplug the vacuum line from the MAP sensor and cover the end of the line.

And what does the exhaust look like coming out of the tailpipe? Black, blue, white, etc?

Does your van go thru antifreeze (or did it ever)?

 

[sxfx]

Ok gentleman it was the fuel pump heh I replaced it runs liek a champ. But I think I killed the starter now, cause when I turn the key it only spins really fast and only catches sometimes and starts up. oh well time to go to napa and get a new one.

Anyone know how long it should take me to replace the starter on this beast?

4.3l V6 btw

Thanks,
Mike

 

[astro355]

Glad to hear you caught it. How did you diagnose the fuel pump?

 

[sxfx]

Tell you the truth I work a lot on Nissans and Mazda's and the symptoms just matched up. So I said screw it fuel pump was only 35 bucks. Except my started went fubar now hehe.

 

[astro355]

Did you check the fuel pressure?