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Engine (RB20) running rough after fuel pump change

R32RB20
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R32RB20 Explorer

R32RB20

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Posted (edited)

My fuel pump died so i swapped for exact same model (Walbro 255). A few minutes after running new fuel pump my engine (RB20) suddenly started acting rough. After cycling on and off a few times the roughness is still there. I couldn't find anything related on the forum. If you have any ideas please throw them my way. Thank you ☺️

Edited by R32RB20
  • R32RB20 changed the title to Engine (RB20) running rough after fuel pump change
GTSBoy Grand Master

GTSBoy

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Posted

Have you measured fuel pressure? Have you gone back into the tank to make sure that it is all still together and shit hasn't fallen apart (bad hose clamp, etc)? Have you got any better details than "acting rough"? Is this just at idle? Will it drive fine at light load but starts to struggle with some load? Ets, etc.

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R32RB20 Explorer

R32RB20

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26 minutes ago, GTSBoy said:

Have you measured fuel pressure? Have you gone back into the tank to make sure that it is all still together and shit hasn't fallen apart (bad hose clamp, etc)? Have you got any better details than "acting rough"? Is this just at idle? Will it drive fine at light load but starts to struggle with some load? Ets, etc.

It rumbles like a boxer engine, the car shakes and on acceleration it initially struggles but then builds rpm consistently (all the while "rumbling")

R32RB20 Explorer

R32RB20

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54 minutes ago, GTSBoy said:

Have you measured fuel pressure? Have you gone back into the tank to make sure that it is all still together and shit hasn't fallen apart (bad hose clamp, etc)? Have you got any better details than "acting rough"? Is this just at idle? Will it drive fine at light load but starts to struggle with some load? Ets, etc.

Where do I test fuel pressure from? The fuel filter? 

GTSBoy Grand Master

GTSBoy

Posted
Posted

Yes, you will need a suitable sized T piece, more fuel hose, a suitable pressure gauge (6 bar should be good) and some hose clamps. insert the T piece in the line between the filter and the fuel rail. Don't cut the existing line. Just undo one end and use some fresh hose for the two** spare legs on the T piece.

**Two if you have the gauge remote located on a short length of hose. Only one if the gauge is straight onto the T with fittings.

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White GTS-T Mentor

White GTS-T

Posted
Posted

If you have not replaced the in-line fuel filter after replacing the fuel pump, which you should have, the filter will be blocked. Remove and test the fuel filter by blowing through it to see if it is restricted and full of contamination (copper etc from the failed pump)

R32RB20 Explorer

R32RB20

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  • Author
Posted

Haven't tested fuel pressure yet as I'm waiting for a fuel pressure kit to arrive. However I have further information which may help:

1. New Walbro fuel pump has a really loud whining, which wasn't present on the old pump (before it failed)

2. Exhuast smells rich

 

 

 

 

 

 

 

 

  • 4 weeks later...
R32RB20 Explorer

R32RB20

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  • Author
Posted

Just pulled out the engine coil valley cover and had a brief test of the ignition cables. I found that the 3 rear (closer to the windshield) ignition cables didn't make a difference when pulled out as opposed to the outside (closer to the headlights) 3 ignition cables which made the car shakes more and nearly stop.

My guess is either the ignition cables or distributor are faulty? How do i test the distributor? Further how do I know it's not the coil pack or spark plug?

GTSBoy Grand Master

GTSBoy

Posted
Posted

Just for come clarity - we need to straighten out terminology.

"Ignition cables" is usually taken to mean the high tension (voltage) thickly insulated spark plug leads used on engines with remote mounted coils.

A "distributor" is a mechanical spark distribution device that distributes the spark out from a single coil to as many cylinders as need it.

You don't have either. What you have is ignition wires (from the ECU to the igniter, and from the igniter to the coils), and the igniter, which is merely a box with 6 transistors in it.

The only way to test the ignitor is swaptronics. Pretty much ditto the coils. If you move a bad coil to a good coil's position and the miss goes with it, it's the coil. But if the miss stays in position it's the wiring or the igniter. Then you swap the igniter to a known good one to rule that out. Or you could swap the coil loom to a known good one to rule that out (they can be bought). Although, I don't know why you would buy either, when you could follow the recommendation I gave in your other thread.

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