MSefi.com read only forum (Jan.15,2018)

I may have blown the fuel pressure regulator in our boat this weekend. I'm using a pump from Summit rated at 100psi to feed a GM TBI unit with stock internal regulator. I've posted about this combination and another user said he had luck with a high pressure pump and TBI so I took a chance with it. I need to remove the regulator to see if the diaphram ripped open.

This engine ran great in the driveway for months, and ran ok on the first test run. The second test run was another story. It idled "ok" but started to stall...then it would start...then it would start and stall and we couldn't even get into the marina. I won't even bother posting an MSQ or datalog because I tried multiple fuel maps and fuel settings with not luck. This has led me to believe that somethign mechanical failed in the TBI causing it not to run correctly.

So if anybody has any suggestions for a lower pressure external pump, I would be much appreciative. I will find out tomorrow if the regulator is bad or not. If it isn't, I don't know where to go from here. Doesn't make sense this thing idled great and started EVERY time and now it won't even idle. So frustrating. Thanks in advanced.

We had no problem using a Walbro GSL392 with a GM TBI, and that's a pretty high pressure, high volume pump.

Matt Cramer wrote:We had no problem using a Walbro GSL392 with a GM TBI, and that's a pretty high pressure, high volume pump.

FWIW, I have been using the same pump as Matt mentions above, for a long time (~5 years) on my original TPI project at ~43 psi. I now use that same pump with a Holley TBI running at 21 psi. I am very pleased with it and have never had a problem.

Ken

Thanks for the input guys. I really won't know where to start if the regulator is not my problem. Unless it's sucking up water or some other wacky scenario. I won't know until further investigation. Any suggestions?

If it ends up that you've blown the gasket in that regulator, and if you don't want to risk it again, you could gut the TBI regulator and use an external regulator in the return line. Mallory makes a $100 version, 1 for high-pressure port EFI and another lower one that's suitable for TBI. They are adjustable, and the spring is probably the only difference.

Ther are also lower-pressure pump available too, but they are usualyl the same ballpark price as the high-pressure ones. Here's a mild shortcut for you.
http://www.summitracing.com/search/Vehi ... Asc&RC=100

I have a diaphram if you need it. I had good sucess with my tpi pump on my tbi unit as well as the others.