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How many PSI should mechanical fuel pump have?


Guest Anonymous

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Guest Anonymous

Car is at local shop and the mechanic is going to test pressure on my mechanical fuel pump. What should it be? I have a '76 with Weber 32/36 setup. I cannot find the desired pressure in the specifications of the repair CD (here at work) and my Haynes manual (is it in there?) is at home.

Does anyone know what the pressure should be reading for a mechanical fuel pump?

TIA

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Guest Anonymous

what you should be concerned with is fuel volume, basically all the pump has to do is keep the float bowl full. If you want to test the pump yourself run the outlet hose into a cup and crank the engine. If you're getting good strong shots of fuel out of it then the pump is Ok. If it's just sort of dribbling out, get a new pump.

Matt

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Guest Anonymous

When I took it off the car. I did not test it with it on the car.

I replaced the pushrod (which did not seem to be worn down). Is there any chance that the lobe on the cam is worn down and not pumping properly? I put a little dab of JB weld on the pump (where the pushrod hits it)to build that up a little. Should I just "nut it up" and buy a whole new fuel pump?

Again, the symptoms are:

Car starts very hard (30-40 seconds of grinding on the starter)

Once it gets going, it runs about 15-20 minutes before stalling out. At this time the in-line fuel filter looks like the level is low. Then restarting is very difficult again.

I cleaned all the filters and replaced fuel line as well. I put in a can of "fuel antifreeze".

Timing has been adjusted by the shop.

I need to get this thing running to put it in off-site storage for the winter.

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Guest Anonymous

can deliver...I have a pressure regulator on mine set at 1 3/4 PSI and it's more than adequate for the 32/36. Did you check the pad on the fuel pump that the pushrod bears against? I've had one worn to the point where even a new pushrod won't deliver a full stroke to the pump. Being cheap, I took the pump apart and welded up the pad to its original height, smoothed it on the grinder and reassembled. Worked like a charm after that.

BTW--The fuel filter always seems to be partially empty, even when the engine is running.

From your description, I would guess there's a leak in the fuel line somewhere between the tank and the fuel pump, the carb float level is wrong or the carb has an external leak. Have you substituted a known good fuel pump to see if the symptoms go away?

Let us know what you find...

Cheers

Mike

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Guest Anonymous

that the pushrod strikes, but have no idea what the correct original height of that is--any idea? I know that it would not hold up in the long run but was hoping to get something functional. Being cheap, I do not want to spend the $ on a new fuel pump until I know that is the problem. I replaced the pushrod; tried building up the fuel pump itself; replaced all fuel lines (except through the passenger compartment). I have not tried a known working pump yet. I got one coming (seller says it worked when removed) in the next week.

I will keep plugging away until it starts/runs as it did in the not-to-distant past.

Chuck

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Guest Anonymous

is the supply hose, any slight leak will greatly reduce pump output, I haven't found my extra pump yet, and all my parts cars were scavenged already, I'll bet I have 10 in a box if I can find it!

Dave

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Guest Anonymous

supply line that runs through the passenger compartment but have checked everything in trunk and engine bay, replacing those lines and cleaning all filters. I will let you know if the pump I get on Ebay doesn't fix the problem. You can quit looking for now! I just cannot figure why it would start acting up ever since that day in September when I went down to Chicago. What did you do to the car when I wasn't looking?

OT--just got done with an awesome batch of homebrew--dark brown ale, almost a stout. One of my best yet IMHO!

Chuck

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Guest Anonymous

a real welder to build up the pad the pushrod contacts. Or if you're REALLLY cheap, find a junk fuel pump and remove the pad from it to install in yours. Someone is bound to have a junk pump...

Mike

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