3.5 psi too much?

I have an electric fuel pump with a 34 pict 3 carb that's been overflowing the float bowl and dumping gas out the tube straight into the throat of the cab flooding it. I took the top of the carb off and the needle valve and float are fine. I just tested the pump pressure and it reads 3.5 psi constantly. Is this too much pressure for the needle and float to hold back?

Thanks for any insight......

Mac

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Mac
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"Mac .net>" I have an electric fuel pump with a 34 pict 3 carb that's been overflowing

Also, this is probably relevant, I had to drain the oil for the second time after it got seriously contaminated with gasoline. It was parked facing uphill with the fuel tank above the carb for a couple of months and, I assume, overflowed the bowl and leaked down the intake. It had a couple of quarts of extra fluid in there, not just enough for an indication of a smell! I changed the float/needle valve after the first occurance and it happened again.

Any help is greatly appreciated.....

Mac

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Mac

Mac "Mac .net>" news:tDJgf.20606$rB3.5441@dukeread02...

Park facing downhill. If the engine is hot or the angle is steep enough, fuel will siphon right out of the brass vent tube and down the throat. This has nothing to do with fuel pressure or the float needle valve.

Maybe install a manual cutoff valve in the fuel inlet.

Speedy Jim

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Speedy Jim

I have it parked downhill now. I still don't understand why it flooded out on me while driving though. After it died I looked at the carb while the pump was still running and it was pouring fuel out the tube. I pulled the pump fuse and drove it the 300 yds home out of the fuel left in the bowl after I got it started. I'll double check to make sure I have the right spacer under needle vavle and it is a Baja so I'm eventually going to have to add an extension to that tube to keep from flooding when I take it off road. I have plans on installing a shutoff valve and fuel pressure regulator I've already purchased on the firewall. You think around 2.5 psi would be good? My manual (bentlys) states for a mech pump it should put out

2.8 psi at 3700 rpm. Thanks Jim!

Mac

Reply to
Mac

Yes, I like 2.5 psi. And the extension tube.

You might also consider a safety shutoff circuit for the pump, if you don't have one.

Look on this page of my web site:

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section/ "Safety circuit for adding an electric fuel pump."

You can also use an inertia switch from a late-model car.

Speedy Jim

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Speedy Jim

Thanks Jim. Looked through your site before and very helpful.... you are very helpfull too with your "Speedy" advice, been reading this group for a few years. On your circuit for an electric fuel pump what is the reason for the push button switch? It appears that when you turn the ignition on the relay makes contact 30 close with 87 giving power to the pump. It might be me..... only used to looking at color VW schematics form VintageBus.com or C-130 schematics, the planes I work on. I'm too beat to hunt down my schematic right now but is the D+ on the battery only hot when it's running? It would make sense for me then so you could prime your float bowl if it sat for a while to get the engine started. Thanks again Jim for the advice..... I'm going to run my pressure regulator as close to 2.5 psi as it will let me, it's a local parts store cheapy one. Thanks again Jim!!

Mac

Reply to
Mac

Yes, D+ is only hot when the Alt is charging (running). And the push button does let you prime the bowl.

Jim

Reply to
Speedy Jim

I've used electric pumps with the same carb and had some problems. I use a fuel regulator set at 2.5 and have no problems. I also use a regulator with a stock pump on the Puma and the dual webers set at 2.5 and they run better also.

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">Den's1977 Puma

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Dennis Wik

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