Ryde _Or_Die

Ok my setup is as follows:

4x720cc injectors
walbro pump
no pulsation damper
s-afc tuned all the way to -50% at 1000 & 2000rpms
heavy streetport
fcd

Now my mechanic says my car will not run unless he pinches the fuel line because its flooding itself up even with the s-afc tuned all the way down. He told me I need a fpr to tune the fuel down even more since he ported the engine and lost vacuum to the stock fpr. Does this sound right?

Tsunami

might be injectors?

maybe overruning FPR (common problem on DSMs with walbro pump.)?

J-Rat

iTrader: (2)

I dont know of any car that would run at -50% correction on the SAFC....

Scott 89t2

pinching the line where? if it's the return line then you are rasing the presure and adding more fuel. because your S-afc is way way too low. try with -25%.

Ryde _Or_Die

Why is that? With stock injectors I was at -20% at least just to save some gas. Now I have even bigger injectors for the primaries.

Ryde _Or_Die

Hes talking about the line coming from the fuel filter.

Scott 89t2

maybe you have a problem with your FPR. stick a pressure gauge on your line

scathcart

A ported engine should still see 14-16 inches of vacuum, so that's not the problem.
Check your fuel pressure; perhaps the FPR is not referenced to manifold pressure?

NZConvertible

The mistakes your mechanic has made so far include not telling you (or not knowing) that all rebuilds flood until they're broken in, not telling you (or not knowing) that -50% on your S-AFC is far too lean, suggesting you need a new FPR when you don't, and not connecting a vac source to the FPR. So far he's not exactly filling me with confidence...

Click here to read about low compression and flooding with fresh rebuilds.

Running the FPR disconnected is very foolish. The FPR is there to maintain a constant pressure differential between the fuel rails and manifold. If there's no vac signal to the FPR you're going to get high fuel pressure differential and rich mixtures at very low manifold pressure (vacuum), proper pressure differential and mixtures at zero manifold pressure, and low fuel pressure differential and lean mixtures at high manifold pressure (boost). So you lose power and response at low load and risk detonation at high load.

Set the S-AFC to -24% across the board to get the amount of fuel injected back to stock mixtures, then get to a dyno and have it properly tuned.

J-Rat

iTrader: (2)

I can kill my car by turning down the corrections at idle..

Ryde _Or_Die

He hasn't disconnected my FPR at all. I know new engines flood.

NZConvertible

So what did you mean by this? And if you know rebuilds flood, what's the problem?

Ryde _Or_Die

I didn't mean he disconnected the stock fpr. Just that he told me that since he ported the engine, I lost some vacuum to the stock one. And my engine floods, but while it is running. It won't stay running unless he cuts some fuel by pinching the fuel hose. If he lets go, it dies.

Aaron Cake

iTrader: (1)

I would think that a -50% value will either completely confuse the stock ECU (after all, it would be an invalid reading), or default it into some fail-safe mode. Your S-AFC is ultimately limited by the stock ECU. Setting a -50% correction is very extreme, and probably way out of range.

New rebuilds will flood and have low compression until they are starting to break in. This could take several hundred miles, especially if the rotor housings used were marginal.

Oh, just another thought...I have seen injectors stick wide open before, and it would produce this symptom. Pop off the upper intake and pressurize the fuel system by jumping the yellow test connector at the passenger shock tower and turning the key to "RUN". Check for injector firehosing fuel into the engine.

Ryde _Or_Die

Alright, will do.