Fuel delivery issue

[movingchicane]

We use the stock fuel line which runs up the left side of the tub along the "frame rail" or whatever that piece of paper mache is called. The exhaust runs underneath the right side. The fuel pump is mounted in front of the left rear axle on the rear bulkhead. The only place where the fuel line is close to heat is when in runs up the firewall and into the carburetor.

Steve,

Its a Carter fuel pump, I think 72gph, 8psi max. Im running about 3 psi. I dont have a fuel pressure gauge in the cockpit but I stuck a guage on it before I put it on the trailer and it was dead on.

Thanks

[steve s]

jeff i thought you had that licked at daytona, with the return line?????
i think your fuel pump may be going bad,or may be an electrical issue, voltage drop when hot.
when you have the problem check for battery voltage at the fuel pump, also check for proper ground. also check fuel pressure and volume cold and hot.
good luck buddy!!!!!!

[CRallo]

Three psi seems low to me but I've never check the fuel pressure on my rx7, its just a street car...

The IT7 guys will have to comment on this one.

Either way, I would mount a gauge on the cowl so fuel pressure can be observed while on track... Looks cool to

[movingchicane]

Three psi seems low to me but I've never check the fuel pressure on my rx7, its just a street car...

The IT7 guys will have to comment on this one.

Either way, I would mount a gauge on my cowl so fuel pressure can be observed while on track... Looks cool to

According to my engine builder and lots of other rx7 gurus as well as what I have seen on the dyno is you need about 2.5 at the needle in the nikki carb. I did mount a fuel pressure guage on the dash last year when I was diagnosing the problem. It was temporary, I dont like fuel lines running in the car even if they are steel braided. Fire is the only thing that scares the crap out of me. On the cowl is not a bad idea

Thanks

[TomL]

Jeff- I'm guessing you still have vapor lock problem. Don't know where you bought your gas for the weekend, but if it was near Rockingham, there are a couple of possible problems. You need low volatility gas to avoid the problem, and the volatility specs for that part of NC are not as tight as in places like Atlanta or Charlotte (for air quality reasons). Second, if it was at a low volume station, you could have even had some left over winter spec (much more volatile) gas, since I think the changeover date is mid-to-late May.

I hate to give away one of my "secrets", but a final fix is to let your gas jugs sit outside for several hours with caps off. It's a form of do-it-yourself volatility adjustment.

[movingchicane]

Tom,

I had that thought too. The car was filled up somewhere in SC on the way up. The fuel we put in before the race was bought in Rockingham. Maybe I got some bad gas.

The fuel jugs were sitting in the garage which was pretty cool so it wasnt hot when we put it in the car. Ive taken that a step further and stuck them in a cooler before.

Thanks

[dickita15]

Are you getting fuel in all 4 barrels of the carb when you rev it?

[movingchicane]

jeff i thought you had that licked at daytona, with the return line?????
i think your fuel pump may be going bad,or may be an electrical issue, voltage drop when hot.
when you have the problem check for battery voltage at the fuel pump, also check for proper ground. also check fuel pressure and volume cold and hot.
good luck buddy!!!!!!

I thought we had it licked too. I think i broke my radio screaming obscenities into the mic when it started missing, i know these symptoms all too well. I hate when stuff like this happens especially when the car has been running so well. We ran at daytona, roebling and kershaw this year and all of those races it was pretty hot and the car was flawless...engine wise anyway, everything else broke.

I actually replaced the fuel pump last year right before daytona so I would be suprised if it was bad but you never know. Battery is a month old and cranked strong after the race. Ill have to check the battery connections and grounds when I get to the shop. Alternator is charging fine. Ill check the pressure/volume this weekend.

Im gonna try and reroute the fuel lines and wrap them. Any suggestions on what to wrap them with? Also looking for any suggestions on lowering the temperature under the hood. Exhaust heat shield, etc...

Thanks for the help