VCCA Home Forums TECHNICAL - GENERAL Trucks and Vans Fuel pump leak

I noticed that my fuel pump is spitting gas out the back side of it. It is an original glass dome mechanical pump. I crawled under the engine and found a small hole a litter bit larger than a paper clip wire on the back side of the pump. It is located below the diaphragm. Does anybody know why gas would be exiting the pump from this hole? When the engine is running, gas sprays from the hole. When the engine is not running, gas weeps slowly from the hole.

I'm considering buying a rebuild kit from The Filling Station. they also sell a new pump. Any opinions about rebuild vs. new, and is the new pump a good product?

Thanks for the help.

A vent. Sounds like the diaphragm has a hole in it. I had a '64 Pontiac that had the same problem when I was on my way back from Florida years ago. A friend had the same problem on his but it caught fire when he was taking it to a garage.
Neil

He is correct. There is a hole in the bottom of the fuel pump body to do just as you describe. When the diaphragm tares and starts to leak it will send some of the fuel to the crankcase. BAD!

I would purchase the new or rebuilt pump. Unless you are an accomplished mechanic and find this job interesting.

Rebuilding the old one isnt that bad. Providing no part of the mechanical insides are wore out, usually just a proper clean up, spray out, rebuild and re-assemble is necisary. It's nothing more than what they do with "professionaly rebuilt" pumps. The only diference is that the individual rebuilding the pump may have many more years of vehicle expertise. But he or she got there by doing the same exact thing you are thinking about. Dont let it intimidate you.

When you do rebuild the pump and re-assemble, the fuel system will need primed though becouse your going to drain some gas when you remove the pump to be built. Usually i just pour some gas down the carb ti'll the engine starts running on it's own.

I am all done with crappy mechanical fuel pumps.
I am converting my fleet over to electric pumps.

Even if you do rebuild your old mechanical pump... it won't be long before todays modern fuels eat through the rubber diaphram & it will start leaking again.

Recently had a faulty leaking original mechanical fuel pump dump raw fuel into the crankcase of my '49.
Oil pressure dropped to zero & the motor started clacking....
I pulled over to check the oil & the dip stick smelled like fuel.

Good thing I shut it down quick or I would have been lookin' at rebuilding the entire engine.

Upgraded to the Bosch/Facet electric fuel pump.... mounted under the inside frame rail next to the fuel tank.

I retained the original mechanical fuel pump on the block for the appearance of originality but, I removed the operating lever that rides on the cam , used a flate block off plate between the pump & block & I put a block off plate in the top of the glass bowl {where the original rubber diaphram was }

I still use the top of the original mechanical glass bowl pump as an inline filter but the pump itself is not operational. { the original fuel lines & pump look stock when the hood is opened}

New electric Pump is run by a toggle switch under the dash { which doubles as a theft deterent}. I also added a small pilot light on the dash to remind me to shut the pump off.

The Facet pump operates at 4.5 to 5.5 GPM just like the old mechanical pump ,and it starts right up without alot of cranking even after the truck has sat for awhile & vapor lock problems are eliminated. It runs quiet & have had no problems with it at all. The Facet pump also has a built in removable & cleanable screen/filter.

May not be 100% correct but... no more worries about a $35 fuel pump ruining a $2000 motor whenever it feels like leaking into the crankcase.

This top quality Bosch/Facet pump will run you in the area of $175 retail each from NAPA but, I found a wholesale source at around $80 with free shipping here....

http://www.racerpartswholesale.com/product/4954/Facet_Fuel_Pumps

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Sometimes life just points you in the direction you need to go.

The Filling Station is out of stock on rebuild kits, but they have a new pump in stock. So my wife and kid - he's been driving the truck on a daily basis - lucked out that with removing 2 bolts, the problem should be fixed in short time this weekend. No keeping the fingers crossed that Dad doesn't forget how all those pieces go back together before Sunday is over.

However, not to be outdone, I doubt I'll be able to keep myself from tearing the original pump apart and getting to the bottom of it. So I'll probably end up getting a rebuild kit when they are in stock and rebuilding the orignal pump for the entertainment value and sense of accomplishment.

Then, if I ever convert from 6V to 12V, I'll start looking at electric components, like a wiper motor too. But for now, I'm sticking to the original design. It's worked for me for over 20 years.

Thanks for all of the advice.

I wouldn't fool around with a old pot metal casting that could be over 50 years old. I would strongly recommend installing a new fuel pump and changing the oil.

What voltage is that pump?

http://cgi.ebay.com/ebaymotors/NEW-...arts_Accessories&hash=item45f6bffcf9

Above is an eBay link to an AC 6 volt electric fuel pump. $48 bucks. P/n EP 11

And below is another AC 6 volt pump for $104 bucks. I have the one below. I didn't pay nearly that much for it.
http://cgi.ebay.com/ebaymotors/NOS-...arts_Accessories&hash=item518d9457f7