95 Astro/Safari Fuel Pump woes VERY LONG!!!!

[my3sonburns]

I have been having problems with a 1995 Chevrolet Astro/GMC Safari. I am hoping someone can help.

I have been having this problem for the past year or so.

Originally, the van would turn over, but not start. I ended up replacing the fuel pump, and the problem went away for about a year. I had to have the motor replaced, because it threw a rod bearing with almost 200,000 miles on it.

Anyway, the van worked fine for a long trip from North Carolina to South Carolina for a few trips. Then, the van was parked in the driveway. The next morning, after a long trip home, it wouldn't start. I sprayed starting fluid and it started right up. I immediately assumed I had the same problem, so I went to Advance Auto Parts and returned my lifetime warranty fuel pump for a new one.

I installed the new pump and within 82 miles, I experienced the same exact problem. Turning over, but hardly ever starts. Then it sudeenly started, so I drove it around the block a few times. After a few good starts, it died on me. I immediately began to check the wiring harness and everything leading back to it. I removed the ground wire and sanded around the terminal and put it back on. Still nothing. I then removed the wiring harness plug (3 wires including the gray) I turned the key forward and noticed that I was only getting 8.5 volts across 2 of the wires, and 0.00 on the other two. I plugged it back up and it wouldn't start. I had my son keep turning the key back and then forward, and eventually noticed that my reading jumped to 12.5 volts across all 3 wires. I plugged the harness back together and the van started. But it only ran for a few minutes before shutting off. I tried starting it again, and when it wouldn't start, I pulled the plug lose under the van and tested the 3 wires once again. I discovered that 8.5 volts on 2 wires and nothing across the other. I began to see a pattern. I removed the line to the fuel filter and turned the key forward. Each time that the fuel pump kicked on, lots of fuel spilled into a bucket that I had placed under the van. I put the line back onto the filter and tried starting it, and the van wouldn't start.

I then removed the fuel pump relay from the firewall and swapped it with the identical relay next to it. Still same issues. So I tried (with my infinite wisdom) to jumper the harness to 12 volts to test the fuel pump wiring. What do you know? I heard something pop under the dash.

Now my Service Engine Soon light doesn't illuminate and the van hasn't even started since. I wonder what I did? I know that relay gets 12 volts from the ECM right? Will I be buying a new computer? I can't locate the fuse that might be the culprit.

Does anyone have any suggestions? Am I anywhere near discovering this problem? Thanks.

[CD Smalley]

Somewhere there is an oil pressure switch. If the engine is not, or the sensor thinks it's not, generating enough oil pressure it will cut off power to the fuel pump. Find this and check it out. I bet it's your problem.

[my3sonburns]

I know where the oil pressure switch is, but there is an intermittent NO start condition. I'll try changing it after I lick this intermittent problem first, but with the key forward, the computer doesn't care about the oil pressure switch, and I still don't get a reading of 12 volts to the fuel pump when it doesn't start.

Just to reiterate:

When I turn the key forward and I read only 8.5 volts at the 3 wire plug going to the fuel pump, I plug it back up, the van does NOT start.

When I turn the key forward and I read 12.5 volts at the 3 wire plug going to the fuel pump, I plug it back up, the van DOES start.

This shouldn't have anything to do with the oil pressure switch, and I don't like just throwing parts at the van for no obvious reason.

[holymix]

If your oil sending unit is the only thing that is running your fuel pump then you will have to replace your relay. It should not be running on your oil sending unit. That will cause extended starts. The other thing you need to check is what the volt are coming out of the relay.The 8.5 is not enough. i assume that your 4.3 is vortec and should be at verry least 55 psi on fuel or it wont start you should check that alsom good luck.and God bless.

[wadee]

I have heard so many posts about the fuel pump on these Astros. I am having a simailar problem with my 93 (115,650 miles vin W). For the last couple months I have had intermittent starts. Then it kept getting worse and wrose untill today when it wouldn't start at all. I have not replaced the fuel pump yet. I am about to replace it. Is there anything I should check first before I yank the pump? Is there a specific pump I should get?

[CM3G]

My fuel pump just went. How long did it take you to replace. Thanks, and good luck.

[holymix]

you should have at leat 55psi of fuel when starting or it will nerver happen that is if your 4.3 is a vortec. change your fuel filter at the same time try to keep more than 1/4 tank of gas at all times that is what keeps the fuel pump cool and lets it have a nice long life. i would replace it with ac delco its worth the few pennys extra. God Bless

[rockout]

Originally Posted by holymix

you should have at leat 55psi of fuel when starting or it will nerver happen that is if your 4.3 is a vortec. change your fuel filter at the same time try to keep more than 1/4 tank of gas at all times that is what keeps the fuel pump cool and lets it have a nice long life. i would replace it with ac delco its worth the few pennys extra. God Bless

Definetly check the fuel pump pressure If its a vortec It should have around 60 psi when you first turn the key on and stay in the 50's after it is running. It the pressure guage jumps around when running the fuel pump pressure regulator is bad.

[rwdriver44]

I had a GMC S-10 did had an intermittant fuel problem. Replaced computer, fuel pump, injector, fuel filter, oil pressure sender unit, then I finally took it to a shop and they replaced the thermastat but could not find anything wrong with car.

I was looking at signals from distributor with a scope and noticed that I was getting an intermittant output from the a hall effect device from distributor. Replaced distributor(price of rebuilt distributer was cheaper than hall effect pickup) and that fixed problem. As far as I could tell, the only function of the hall effect pickup was to tell the computer that the engined was turning thus enabling the the fuel injector(s) to operate.

Haynes auto repair book reports that some models of astros' and safaris' distributors have a hall effect pickup device. Does not describe its purpose though.

RW

[guyonearth]

If you don't have at least 12 volts at the fuel pump, you need to find out why. You can replace the relay, but these are not usually the problem. What often happens on these vehicles (has happened to me twice) is that there is a break in the insulation in one of the wires driving the fuel pump. Actually only one wire runs the pump, the others are ground, fuel level, and low fuel warning. You may need to peel apart the wiring harness to find the break, and repair it by soldering in a new section, and sealing it with silicone grease and heat shrink/friction tape. Do it carefully or you are wasting your time as it will quickly corrode again. As far as the "hall effect" sensor, yes, it does send a tach signal to the computer, which in turn sends a pull-in signal to the fuel pump relay. This is to ensure that the pump only runs when the engine is turning. All vehicles use some version of this system. Some do it with two relays rather than one. Other than that, the Hall Effect sensor is what triggers your spark, it is basically an electromagnet that produces a current when a sprocket on the distributor shaft passes by it. This triggers the coil to produce your spark to the spark plug.

[Kings-x59]

I can't comment on the burned wire, but there is a very long thread concerning fuel pump problems.
After replacing many parts including the catalytic convertor the culprit turned out to be the fuel pump pulsator.
I can't recall who posted the thread, but you might try a search with the key word "pulsator".
According to autozone.com the pulsator for the '95 costs $14.
The blurb on the web page says this: INSTALLING A FUEL PUMP PULSATOR WITH THE FUEL PUMP
WILL ELIMINATE FUEL PRESSURE LOSS AND NOISE CAUSED BY VIBRATION.
Sorry the caps aren't mine, I'm not yelling, just a lazy typist - that's cut n paste for ya.

[roadrunner_70]

Guy I work with had a no start condition with no prior symptoms. Did some testing and figured it to be the fuel pump. Took the tank off and removed the sending unit, and sure enough, the wires inside the tank had the insulation worn off and there was obvious melting of the connector. Not something you want going on inside your gas tank! He replaced the pump and managed to get the wiring from another pump. All is well. Polarity is critical if you are changing the wires. Don't assume that because the wiring harness looks the same, that it's wired the same. He made this error and had to remove the tank to correct it. Aftermarket pumps don't include this wiring. So, you might want to check their condition before you buy that new pump.

[borka]

please hel to find pulsator location , and can somedy advice me should i change pump also ,or not . because my 95 astro won't start when cold ,and i think is pulsator .