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Fuel pump runs but no flow to rail

donkeylips

Well-known member
Joined
Jun 18, 2009
Messages
552
Location
Rochester, NY
This is a GGSX we just put back together with parts from a VR4 donor car. The car has a completely stock setup. It has the factory fuel feed line from the pump to right before the front subframe where it attaches to a -6 fuel feed line. Then it has an aftermarket fuel filter, and a -6 line from the filter to the rail with an STM fitting.

The car came with a 255 pump(not rewired) and when I went to start it for the first time it would just crank and crank. So I took the feed line off the rail, put 12V to the check connector and could hear it running but no fuel came out.

So first I swapped in a known good stock sending unit assembly. Pulled it right off of a running car. It behaved exactly the same way as the 255.

Then I disconnected the line before the fuel filter to eliminate that as the cause and still nothing. After feeling the lines and disconnecting them at the pump, I have determined that it is definitely flowing, and at least gets to about halfway up the length of the car. I'm pretty sure I don't have any blockages in the lines.

So does this mean that the problem must be that the pump isn't getting enough voltage? Should a rewire solve this issue? I need to move the car from where it's sitting today... is there a quick temp fix I should try?


After looking at the manual, I'm thinking I should look at the fuel pump connector(E33) and check my voltage across pins 1 and 3 while applying 12V to the check connector. I can do this on my 2 GVR4s to compare and see if I get a different value.
 
Last edited:

IncorpoRatedX

Well-known member
Joined
May 28, 2003
Messages
5,593
Location
Arizona
seen this happen when the pump isnt connected properly to the sending unit assembly, could be a situation of the pump picking up fuel, then pushing it out back into the tank through a loose connection. check your hoses/clamps/etc in the sending unit to be certain all the fuel it's picking up is being pumped into the line.

if it is. i'd hot wire the pump, then check blockages.
 

donkeylips

Well-known member
Joined
Jun 18, 2009
Messages
552
Location
Rochester, NY
This is your old car by the way!

Well, 2 different sending units are doing the same thing, and both have now been tested on one of my vr4s. So I've ruled out a problem with them.

I had 12.5V across the battery and 12.0V across pins 1 and 3 at the pump, with the test connector connected to the + terminal of the battery, which didn't tell me that there was a problem there. I connected another fully charged battery directly to these and again heard it run, but still not enough flow.


...So it must be blockage in the lines or I'm really stumped. Luckily I have a spare -6 line that happens to already be assembled to the proper length. I'm going to toss it in there and see what happens.
 

IncorpoRatedX

Well-known member
Joined
May 28, 2003
Messages
5,593
Location
Arizona
I would run new line, that car has been sitting for a long time now. Who knows what's happened to the line.
 

donkeylips

Well-known member
Joined
Jun 18, 2009
Messages
552
Location
Rochester, NY
The new line did it. Now we have no spark...
 

donkeylips

Well-known member
Joined
Jun 18, 2009
Messages
552
Location
Rochester, NY
Sure has spark now! I had the TPS and CAS connectors switched /ubbthreads/images/graemlins/banghead.gif. Runs like a top and made the 5 mile journey to its new location. I'm going to try to drive it 70 miles in a few days.
 
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