Auto Racing: Losing power exiting corners, fuel pressure gauge, datsun 240

Question
Dan,

Hope all is well.  I have a 93 Eagle Talon, and race on a 4/10 mile asphalt circle track.  This weekend, the car started to stall when I would exit corners.  We found a loose clamp on the air intake, emptied the fuel tank (stock tank), changed the fuel filter and had the injectors clean.  

I have no way to test this before going back to the track next week, so wanted to see if you could give me other items I should be checking before going racing next week.

Thanks for you help!

Dave

Answer
Yes, Dave:

It sounds like a fuel pressure problem. This can be a failing fuel pump, a clogged fuel line, clogged filter, or a pressure leak somewhere along the delivery and/or return lines. It might also be a faulty check valve though I'm not sure how.

It's likely that your fuel pump is located IN the fuel tank, for reasons that escape me, manufacturers started doing this in the 90s making the pumps miserable to access, and quite expensive at the same time.

You will have to obtain a fuel pressure gauge, I suggest Summit Racing (www.summitracing.com) where you can choose from several high pressure gauges. The SAFEST ones are those that use an intermediate diaphragm to keep the pressurized fuel outside the cockpit. But the cheaper gauge is OK if you mount it outside, in view of the driver. Your factory manual should tell you what fuel pressure should be, and if it''s notably less, that is the cause of your stalling.  All that's left is to determine WHY it's low- - -and replace the fuel pump with one more suited for competition  (also from Summit) I doubt that your loose intake clamp was the cause.

Now here's a story for you , so you will know how devious pressure problems can be.  My friend's Datsun 240=Z would stall almost precisely at about 155 MPH whether at Sebring or Daytona. It took a while to find that the culprit was a piece of faulty hose with a failed inner liner that was collapsing and blocking the fuel flow. If you still have the stock fuel hose on the car CHANGE IT to the stainless braided stuff like Aeroquip or Earl's .

That's about all I know about that !

Good luck

Dan Liddy
Sarasota, Florida