I have a L69 set up with mechanical pump that starves for gas when hot. I was wondering if stock TPI pump would work with mechanical. I already have fuel pump and sending unit.

 

TPI pump is going to have alot of pressure (like 40-something psi) - don't know that the mechanical fuel pump can take the pressure from a TPI pump. But a Mallory 4309 regulator would solve the issue, then you could get rid of the mechanical pump.

But mechanical pumps have been feeding huge motors for years - are you sure it's a fuel issue, and not a timing issue or some other problem? I mean let's face it, until just a few years ago NASCAR ran mechanical pumps, and I'll guess your not running quite that amount of power.

 

Many of the L69's had an in-tank electric pump from the factory to push fuel up to the mechanical pump and prevent hot fuel issues. If yours has the pump, and it has failed, hot issues will be worse than not having any pump.

For the record, a pump doesn't put out any pressure unless there is a restriction on the outlet. A TPI pump won't put out any more pressure than the mechanical pump's bypass allows. A TPI pump might be overkill, but it wouldn't cause overpressure if you use it as a pusher pump up to the mechanical pump.

 

My car does not have factory pump....so if I use the TPI pump I will not need regulator? My current set up is an L98 with aluminum Vette heads,ZZ383 roller camshaft,performer intake and computer Q jet. Car has gone 12.31 @109. On hot days when raceing car noses over during 2-3 shift. This is a steet car with A/C so it does build up alot of heat.

Thanks for your help
Frank

 

Carbs love volume...not pressure so if you use only the TPI pump, you will need a regulator to bring the pressure down to no more than 6.5PSI. Any more than that and you risk gas overfilling the bowls and spilling out of the carb.

 

You need to update your sig and/or sidebar info - we have no clue even what car you have, and no info on it, so we don't know if your car has an intank helper pump or not. OK, now we know what motor etc, but we still don't know what year of car - maybe it has an in-tank pump that you aren't aware of? Just because there's a mechanical pump on the block doesn't mean there was never an electric helper pump in the tank. Was it a V6 car? I don't know much about V6 cars, but maybe the mechanical pump for a V6 won't feed that motor?

If it's strictly a mechanical pump system, then you have another issue somewhere maybe. Mechanical pumps have been feeding motors much larger/faster than yours for many many years now. Maybe you just need a better mechanical pump, or maybe you have another issue.

 

Not a problem. A V6 mechanical pump won't fit on a V8...

I'd like you to make sure about the in-tank electric. On carb cars that have them, when they go dead, all sorts of problems crop up.

 

Then that solves that issue. Told ya I didn't have any V6 knowledge!

 

I had the pusher pump in my 84 305...never had a problem until I did the motor swap and didn't have a mechancial fuel pump anymore (Engine wasn't drilled for the pump rod). Putting two holley and one Aeromotive pump in line and burning them all out roughly 4 months apart made me pull the tank to check the filter only to find a pusher pump. I had no power going to it through the sender, checked all the lines so it may have been working, but with no power, it never stood a chance. Also the car ran fine for 7 years...right up until I didn't have the mehanical pump, apparently they are more powerful than the inline electric pumps. The one in the tank caused enough of an blockage that it was causing my pumps to burn out.