No Fuel Pressure
Thread Starter
4th Gear
Joined: May 2025
Posts: 4
Likes: 0
No Fuel Pressure
Last weekend I replaced the fuel pump and fuel filter in my 86 C4. Drove it for a few days without issues but now it will not start. Checking fuel pressure it is at 0 and I do not hear the fuel pump turning on. I replaced the fuel pump relay and that did not resolve it. The fuel pump fuse is good and been replaced to ensure but still no luck. Any ideas?
Drifting
Joined: Nov 2018
Posts: 1,787
Likes: 579
From: Mays Landing, NJ
If you are not hearing the pump come on there is a reasonable chance that the pump itself is bad. Sometimes new parts do go bad and I bet that is what happened to you if you are getting 12 volt at the pump.
Safety Car
Joined: Mar 2003
Posts: 3,583
Likes: 504
From: Indianapolis IN
Finalist 2020 C4 of the Year - Unmodified
C4 of Year Finalist (stock) 2019
I completely agree. What you didn't mention was: Did you replace the pump with a QUALITY replacement pump, or did you go on the cheap and buy some RockAuto or Amazon el-cheapo Chinesium unit? Some parts are worth the extra money for a quality part, and this is one of those parts.
Thread Starter
4th Gear
Joined: May 2025
Posts: 4
Likes: 0
I completely agree. What you didn't mention was: Did you replace the pump with a QUALITY replacement pump, or did you go on the cheap and buy some RockAuto or Amazon el-cheapo Chinesium unit? Some parts are worth the extra money for a quality part, and this is one of those parts.
Burning Brakes
Joined: Jun 2005
Posts: 1,188
Likes: 13
From: Wallingford Vermont
I hate to say this, but there have been many instances of Chinese knock-off fuel pumps sold through Ebay and Amazon. Usually it's Walbro clones.
First, do you have voltage going to the fuel pump? A test light can tell if it energizes on initial "key-on" and the again when the oil pressure switch engages during cranking/starting. Beware of using a multimeter, cause you can be fooled by voltage but inadequate amperage (like a bad ground).
Next, did you reuse the pulse dampener on the fuel pump or did you use a short connecting hose? I've seen cheap hoses split after being immersed in fuel for a while. And I've had some personal reservations about whether my pulse dampener was sealing adequately (so I ditched it).
Lastly, yeah I've seen new parts crap out. I had a bad Delco Remy alternator (new) that had a bad winding. It would drop voltage occasional once the RPM climbed about 4K.
First, do you have voltage going to the fuel pump? A test light can tell if it energizes on initial "key-on" and the again when the oil pressure switch engages during cranking/starting. Beware of using a multimeter, cause you can be fooled by voltage but inadequate amperage (like a bad ground).
Next, did you reuse the pulse dampener on the fuel pump or did you use a short connecting hose? I've seen cheap hoses split after being immersed in fuel for a while. And I've had some personal reservations about whether my pulse dampener was sealing adequately (so I ditched it).
Lastly, yeah I've seen new parts crap out. I had a bad Delco Remy alternator (new) that had a bad winding. It would drop voltage occasional once the RPM climbed about 4K.
Thread Starter
4th Gear
Joined: May 2025
Posts: 4
Likes: 0
I hate to say this, but there have been many instances of Chinese knock-off fuel pumps sold through Ebay and Amazon. Usually it's Walbro clones.
First, do you have voltage going to the fuel pump? A test light can tell if it energizes on initial "key-on" and the again when the oil pressure switch engages during cranking/starting. Beware of using a multimeter, cause you can be fooled by voltage but inadequate amperage (like a bad ground).
Next, did you reuse the pulse dampener on the fuel pump or did you use a short connecting hose? I've seen cheap hoses split after being immersed in fuel for a while. And I've had some personal reservations about whether my pulse dampener was sealing adequately (so I ditched it).
Lastly, yeah I've seen new parts crap out. I had a bad Delco Remy alternator (new) that had a bad winding. It would drop voltage occasional once the RPM climbed about 4K.
First, do you have voltage going to the fuel pump? A test light can tell if it energizes on initial "key-on" and the again when the oil pressure switch engages during cranking/starting. Beware of using a multimeter, cause you can be fooled by voltage but inadequate amperage (like a bad ground).
Next, did you reuse the pulse dampener on the fuel pump or did you use a short connecting hose? I've seen cheap hoses split after being immersed in fuel for a while. And I've had some personal reservations about whether my pulse dampener was sealing adequately (so I ditched it).
Lastly, yeah I've seen new parts crap out. I had a bad Delco Remy alternator (new) that had a bad winding. It would drop voltage occasional once the RPM climbed about 4K.
Replaced the fuel pump again and now it is working.
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