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Fuel pump running, but no fuel pressure


Helterbot
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I'm trying to get my car started after being down for 4 years, but I'm not seeing at  fuel at the throttle body. I used the jumper on the passenger side engine compartment to test the fuel pump, and you can definitely hear it running. I removed the fuel filter and put the fuel line into a bucket and powered the pump for a minute, but nothing ever came out.

What would cause this to not work? Is it likely that something is clogged? The tank is full of non-oxy gas that had Stabil in it, so I'm hoping it didn't completely turn into sludge in the 4 years that the car has not been running. Any input would be appreciated.

 

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I tried disconnecting the line at the pump, but I still didn't get anything out. I took off the driver's side rear wheel and there is a rubber line that connects to a metal line, and that's what I disconnected. What this where you were thinking I should check?

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Here's the hose I disconnected. I jumped the pump with the connection under the hood for about 15 seconds, but nothing came out. Let me know if this is the wrong approach.

20211114_133637.jpg

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That appears to be the return line, it won't help (it may be the vent, I can't tell in the photo..but it's definitely not the line you want).   The high pressure feed line is the one wish swaged connectors that connect to the steel line via the proper threaded adapters.   I just posted this photo for another member, its the large line with the female threaded end.

full

You can access this line by getting under the car and looking up between the tank and the rear.    Sometimes this joint is hard to separate...don't break your steel fuel line!   

Another thing you can try is to remove the access door in the trunk and pull the hose for the pickup tube.  Insert a new hose into a gallon of gas and fire up the pump to see if it sucks any through.   

 

Three things could be the problem:

1. You have a clog in your high pressure line somewhere 

2. You have an issue with suction...rusty tank, clogged fuel sock, etc.

3. The pump could simply be bad.  Just because it spins, doesn't mean it works.  

If you unhook the feed line and try suction out of a gas can (both at once), and it still doesn't work, then it is your pump.   

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I took the pickup tube out and inspected it today. I was able to confirm that none of the ports are blocked, I I think the filter is probably fine. Do you think it would be okay to disconnect the fuel filter under the hood, then shoot some compressed air through the line connected to the pump and see if anything comes out? I'm unsure if blowing air through the pump is a bad idea, but I have seen that suggested online for other types of cars.

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Have you checked the small cone filter that is inline before the fuel pump? Most members have replaced it with a inline filter (wix 33500). Sometimes the fuel pump will hum but that doesn"t mean that it is pumping properly.

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Sorry, The wix 33500 is for the underhood fuel filter. The wix 33299 fuel filter is installed inline prior to the fuel pump between the fuel pick up and the fuel pump.

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I'll have to take a look. You get at that though the access panel in the trunk? It's so hard trying to work in that small area. I'm going to try blowing out the fuel lines tomorrow so I'll see if I can find it.

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It is pretty easy to get to the fuel pick up and the hose that goes to the fuel pump from the small access panel. A few screws and some plastic keepers. You can install a inline fuel filter after that. I cut out the sheet metal in that area and installed a cover. Now I have access to the fuel pump without having to drop the fuel tank.

 

Bill

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I have blown air through line with filter disconnected with good results, just use something to catch the gas that may come out. I had done this in my early days with no catch and had the line at rear before pump whip and spray gas at a halogen light. 

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I blew the lines out. I filled the lines with Seafoam and I'm going to let that sit for a bit. It seems like both lines had a little resistance when I started, but the high pressure line was a lot worse. I used a vinegar jug as a catch can. it worked out pretty well.

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Let us know if that worked. I would still make sure that the fuel pump is pumping out the correct fuel pressure. And the only way to tell is to install a fuel pressure gauge on the top hat of the injector housing. Just for my curiosity, is the stock fuel pump still installed? If so, I would replace it with a Walbro GSL-392 fuel pump and installation kit 400-952.

 

If you have any questions post back,

Bill

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The fuel pump is an upgrade, but I bought it from CNM, so I think it was probably around 98 when it was replaced. I saw in the service manual they listed a block that you could attach to the throttle body to attach a fuel pressure gauge, but I wasn't able to find the part available anywhere.

I'm guessing if I have someone jump the pump I should be able to feel some suction of I put my finger on the hose that connects to the pickup tube?

 

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4 hours ago, Helterbot said:

I blew the lines out. I filled the lines with Seafoam and I'm going to let that sit for a bit. It seems like both lines had a little resistance when I started, but the high pressure line was a lot worse. I used a vinegar jug as a catch can. it worked out pretty well.

Message_1637775564690.jpg

 

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I was looking at your picture. Where is the fuel inlet hose? Never mind, i saw it in the vinegar bottle. Just out curiousity, where exactly are you blowing compressed air  through the lines, is it before or after the fuel pump.

Edited by Caliber308
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I disconnected the line that connects to the pickup tube in the tank, so I was blowing air through the pump. For the return line I disconnected it at the tank and disconnected it from the throttle body and blew from the back of the car to the front.

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It looks like clogging was the issue. I tried jumping the pump yesterday and fuel immediately came out. I was able to get the car started, but I'll need to get the brakes sorted out and get tabs before I can go anywhere. It'll probably have to wait until Spring.

 

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6 hours ago, Helterbot said:

It looks like clogging was the issue. I tried jumping the pump yesterday and fuel immediately came out. I was able to get the car started, but I'll need to get the brakes sorted out and get tabs before I can go anywhere. It'll probably have to wait until Spring.

 

Glad you are getting fuel now. You really should install a inline filter between the pick up tube and the fuel pump. Getting the car started and having the proper fuel pressure are two completely different things. There is a write up in the FAQ section on how to install a fuel pressure gauge on the top hat. It is not that hard and may save you headaches down the road, especially on boosting.

 

Just for some future reference. If your car has sat as long as Helterbots did.... don"t try to start it until you clean the "disconnected" fuel lines out and replace all the fuel filters. Then, after you drain the fuel tank, fill it with 5 gallons  of 100 octane racing fuel, start it and let it run for at least 30 to 45 minutes.

 

Bill

Edited by Caliber308
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