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1995 Astro van won't start
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f0rpleazure
New User
Sep 1, 2006, 6:50 AM
Post #1 of 5
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1995 Astro van won't start
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This van will crank but won't start. I cannot hear the fuel pump running, I removed the fuel filter, not clogged, and the fuel pump did not work. This van is a CMFI so it has a fuel pump relay but I cannot find it. The repair manual says the relay is in the convenience center under the center of the dash. I would like to get to this relay, it is much cheaper and easier to change. I also wonder if the oil pressure switch could be cutting off the fuel pump, and where is this oil pressure switch? Any help on this will be greatly appreciated.
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DanD
Veteran
/ Moderator
Sep 1, 2006, 10:41 AM
Post #2 of 5
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Re: 1995 Astro van won't start
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According to my information the fuel pump relay is under the hood, above the heater blower motor?
An easy test for the relay is to check whether there is power on the gray wire at the relay during cranking. This gray wire will also be found at the oil pressure switch and then at the fuel pump itself.
The oil pressure switch is at the top of the engine close to the distributor; you will likely have to remove the engine cover to get at it.
Its function in regards to the fuel pump circuit is to be a back-up means of supplying power to the fuel pump, if the relay fails. It is NOT designed or intended to shut the pump off if there is a lack of oil pressure. (Even though it does after the ignition is shut off; I’ll explain later)
If the relay is functioning properly the fuel pump will continue to be powered regardless of oil pressure, until the computer looses the RPM signal and turns the relay off.
Here’s how the system is suppose to work, this is if the relay fails and the relay is the only problem in the circuit.
You begin cranking the engine; the pump is not being powered up by the relay; you continue to crank the engine, oil pressure starts to build. Once the pressure reaches approximately 4psi the connection inside the pressure switch closes, sending power to the pump and then the van starts. A GM with a bad relay will start but it usually takes about twice as long in cranking the engine; that’s until the engine builds oil pressure to close the switch powering up the fuel pump. Again this is only if the fuel pump relay is the only fault.
I think most people that drive GM’s have heard the fuel pump still running for a couple of seconds after the engine has been shut off. The oil pressure switch is the cause of this and it’s “normal”; oil pressure has to drop below 4psi before the switch will open the connection.
What I would do is go under the van and find the wiring harness connector for the fuel pump and test the gray wire there for power during cranking. If it has power then you know that the relay is functioning because that is the last connection before the pump that you can get too without dropping the tank.
You’ll find this connector on the inboard side of the left frame rail below the drivers seating area.
If there is power at this connector you more then likely have a bad fuel pump.
Dan.
Canadian "EH"
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Sep 1, 2006, 5:23 PM
Post #3 of 5
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Re: 1995 Astro van won't start
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Just a note here: I own three Fords and they all have universal relays in glove compartments because I've been stuck too much because of them.
On some you can take the A/C relay out and put it in other locations just to get going. The older ones were NOT marked and many newer ones are and are interchangagle but always read the part #, T
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f0rpleazure
New User
Sep 4, 2006, 6:37 AM
Post #4 of 5
(10617 views)
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Re: 1995 Astro van won't start
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Dan, certainly appreciate your information. You saved me a lot of time digging for that relay. I tested the gray wire and immediately was able to determine it was the fuel pump. I replaced the fuel pump, grueling process, and the van is now up and running. Thanks again!
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DanD
Veteran
/ Moderator
Sep 4, 2006, 10:34 AM
Post #5 of 5
(10613 views)
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Re: 1995 Astro van won't start
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Thanks for the fix post.
Dan.
Canadian "EH"
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