My '92 TransAm won't start and fuel pressure drops as soon as the pump stops priming. I'm assuming the diaphragm in the Holley AFPR has given up but I called Holley and they said they don't sell just the diaphragm. Anyone know if there's a compatible diaphragm I can buy? $155 for a new Holley one.

 

to find an internal part number for the diaphragm assembly. Part number 35R1998A. This is not a retail part number and you would need to call into the tech line to order one as a special order item

 

Thanks. They're pretty proud of their diaphragms. $73.40 with S&H and zero currently on hand. If it goes more than a week I'll cancel and just go a different route.

 

That’s better than the whole assembly. But yeah not cheap. Does fuel pressure hold with rubber return line pinched ?

 

If I remember right, I modified the stock one
and it worked. Because the Holley is poor quality.
Not too much different in cost tho.

https://www.rockauto.com/en/catalog/...regulator,6124

 

Thanks for the suggestion. It's been a while since I've tinkered with TPI. I have a Vortech supercharger kit on it and pinched the line off near their booster regulator. The pressure spikes to 80 while priming and then drops off. I took the vice grips off and was able to start the car this time but ran really rough. Idle was 30 PSI but I did some custom tuning a while back and cut the pulse width down. Maybe its not the diaphragm after all. I remember having a bad diaphragm once and think the vacuum line was sucking fuel into the intake and one of the runners.

 

Or this:

AFPR.pdf

With this:

https://tpis.com/products/1_fpr002?v...28342555050056