v6 fuel pump vs v8 fuel pump

[Shea_G]

I recently did a v6 to v8 swap in my regal 2100. At about half throttle I'm up to about 4000 rpm and when I give it more the engine starts to bog down until I back the throttle off leading me to believe it's a fuel delivery issue. Checked the filter, looks fine and I replaced anyways. Tried two different carbs, made no difference. I'm getting 7 psi at idle but unfortunately haven't checked under load. Is there a significant difference in fuel volume that a v6 fuel pump is capable of passing through? Or are they the same pumps all together? I didn't swap pumps when I get the engine swap. Seems to me, thinking about it that the pump is pushing as much fuel as it can and it's just not enough for the v8.

 

[Rick Stephens]

Mercruiser used different fuel pumps for 4.3 and bigger V8s.

 

[Bondo]

Ayuh,.... While yer issue seems to be fuel delivery, a V6, 'n V8 fuel pumps don't matter,....

 

[gm280]

I take it these were both carbed engines. And if so, the needle and seats would basically be the same type and that would mean they both can work properly with either pump. I'd be more concerned if you were starving for fuel then over fueling the engine... So I say it should make any difference... JMHO!

 

[Shea_G]

Hmmm, guess that rules out the pump. I'm lost as to what to check next.

 

[Bondo]

Ayuh,.... Hook up a remote gas can to the fuel filter, to eliminate the boat side of the fuel system,....

 

[HT32BSX115]

I'm getting 7 psi at idle but unfortunately haven't checked under load.

Hook up a gage and run it up to WOT while someone checks the pressure.

If you maintain pressure, it's not a fuel delivery problem up to the gage that is..........

 

[Rick Stephens]

Bondo nails the next step. There are a bunch of possible constriction places - like venting, anti-siphon, filter, bad hose, or even the pump.

 

[Shea_G]

Hook up a gage and run it up to WOT while someone checks the pressure.

If you maintain pressure, it's not a fuel delivery problem up to the gage that is..........

Yea that's my next step for sure.

 

[Shea_G]

Bondo nails the next step. There are a bunch of possible constriction places - like venting, anti-siphon, filter, bad hose, or even the pump.

I can try that aswell, run the pickup hose that comes out of the fuel filter to a gerry can?

 

[Rick Stephens]

Either way works. I didn't see the post by HT32BSX115 before I posted, that is just as good from a different direction.

 

[smokeonthewater]

Not a Gerry can.. A portable marine fuel tank...
6 gallon I common an available cheap about anywhere.

 

[Bondo]

Not a Gerry can.. A portable marine fuel tank...
6 gallon I common an available cheap about anywhere.

Ayuh,..... I've used an ole antifreeze jug in a desperate diagnosis before,....

Common sense, 'n careful plannin' oughta keep ya Safe,...