Jeep fuel pump update

[Little Jo]

Hi Guys

I was having a bit of a fuel starvation problem with my 1942 MB Willys Jeep. I found that I was not getting any fuel to the carby, even with using the hand primer. I dropped some petrol into the carby and she fired up immediately, however no fuel was getting to the carby via the fuel pump. I removed the fuel pump and found that the diaphram was not working properly.

I am now wondering should I repair the manual fuel pump, or replace it with an electric fuel pump. My questions To the MLU members are:

Has anyone out there replaced their fuel pump from a manual to an electric fuel pump and is there any benefit to changing from a manual to electric fuel pump system.

Cheers

Tony

[Richard Farrant]

Originally Posted by Little Jo

Hi Guys

I was having a bit of a fuel starvation problem with my 1942 MB Willys Jeep. I found that I was not getting any fuel to the carby, even with using the hand primer. I dropped some petrol into the carby and she fired up immediately, however no fuel was getting to the carby via the fuel pump. I removed the fuel pump and found that the diaphram was not working properly.

I am now wondering should I repair the manual fuel pump, or replace it with an electric fuel pump. My questions To the MLU members are:

Has anyone out there replaced their fuel pump from a manual to an electric fuel pump and is there any benefit to changing from a manual to electric fuel pump system.

Cheers

Tony

hi Tony,

With you being in Aus, I can recommend the fuel pump repair kit marketed by MV Spares in Sydney ( no connection ! ) as being of good quality, also check for wear in the pump. I would also check that your fuel lines back to the tank are clear. On a recent jeep restoration, it was found that the pick up pipe within the tank was blocked/restricted.

regards, Richard

[Richard Coutts-Smith]

Tony,
Richard F is spot on, check the fuel line right back to the tank inlet. Took us 12 months to find that a beetle crapace was causing the intermittent fuel problems in the Jeep: in effect we had a butterly valve in the first inch of the fuel intake. Ended up with extended bolts on the fuel pump to make it easier for removal, it was coming off so often. Finally diagnosed the problem (arrived at camp in the mountains at 2.00am perched on the mudgaurd pouring chainsaw fuel into the carby) by running a bit of scrounged poly pipe straight to the tank from the pump. This bit of Bush Mechanics got us the 200 kms home, and as it by passed the original fuel line and filter, pinpointed the problem for us.
Have seen a few vehicles fitted with electric pumps, some Champs have an issue with vaporisation, and most also have an abnormally long fuel line. Often the pump is used just on start up to get fuel through to the pump.
Personally my preference is to stick with the original set up, on the KISS principle. However it is quite easy to hide the modification so no one will be the wiser.
Rich.

[Little Jo]

Originally Posted by Richard Farrant

hi Tony,

With you being in Aus, I can recommend the fuel pump repair kit marketed by MV Spares in Sydney ( no connection ! ) as being of good quality, also check for wear in the pump. I would also check that your fuel lines back to the tank are clear. On a recent jeep restoration, it was found that the pick up pipe within the tank was blocked/restricted.

regards, Richard

Hi Richard

Thanks mate, good advise. I will start a search starting at the fuel tank and follow the line to the carb. I have cleaned the fuel filter and there was some muck in there, but not much. I tried to remove the worn diaphram, but even with the manual at my side I could not remove it, hence my thought of an electric fuel pump. I will contact Darcy at MV Spares and see what he has.

I must come clean and advise that I am embarrased to admit that a few weeks back I took the Jeep for a drive through the hills and ran out of petrol coming back home and had to have the RAA (Auto Club) bring out some fuel. But what is worse I have a perfectly good working fuel gauge.

Cheers

Tony

[Richard Coutts-Smith]

Tony,
It happens to the best of us! None of the Jeep guys here rely on the fuel gauge, they all carry a short bit of broomstick under the seat, for dipping the tank. Someone actually went to the trouble of draing the tank, than filling a gallon at a time, marking each gallon on the dipstick, and is believed to be the most accurate Jeep fuel gauge around...
The fuel problems discussed previosly started after the Jeep ran out of fuel on a run (I did say it happens to the best of us), do not think the tank had been cleaned well enough, managed to drag the crap in with the last of the petrol.
Rich.

[Richard Farrant]

Hi Tony,
There is a knack to removing and fitting the diaphragms, there is a slot at the end of the spindle and it hooks ito the lower arm. When you fit the new one, remember to fit the spring first !

The pick up pipe in the tank is in the higher level of the tank and drops down inside to draw from the deep part of the tank, not easy to see if it is clear, best drain tank and put an airline to it.

[Little Jo]

Hi to the two Richards

I have taken what you have said onboard and stick to the mechanical original fuel pump. I stripped down the fuel pump and noticed the diaphragm had given up and It looks like I will now only have to replace the Diaphragm, gaskets and Valve Kit. I ordered them from MV Spares a couple of minutes ago. I then got the compresor out and blew out all Lines from the fuel tank to the carby. so once I get the new repair kit I will get her up and running. I love the idea of the bit of broom stick, I will get a piece myself and mark it as a backup to dip before any drive. Thanks guys for your assistance

Cheers

Tony

[motto]

I purchased a Dodge Weapons Carrier many years ago that had been fitted with an electric fuel pump wired to run whenever the ignition switch was turned on. It was a 12 volt truck so the battery was in a stowage box in the tray body and the battery lead passed through the pedal mount area as does the fuel line.

One day when I was manoeuvring the vehicle close to the house I stalled the engine and when I pushed the clutch pedal down there was a very audible arcing type noise and the amp gauge flickered wildly. I got out and lifted the bonnet to have a look and was shocked to find the battery lead had shifted and been rolled between the clutch pedal arm and the edge of the chassis which had peeled the insulation off. There were flash marks on the nearby fuel line which was a copper replacement.

If luck had been against me I could have blown a hole in the fuel line and the Auto Pulse would have worked its little heart out to feed the fire. There was a distinct possibility of loosing not only the vehicle but my house as well.

Modern vehicles with electric fuel pumps have to have them powered in such a way that they cease operating if the engine stops so as the fuel supply ceases in event of an accident.

In regards to WW2 vehicles, the original mechanical fuel pumps with hand priming are perfectly adequate if in good condition. The greatest exception to that is the Ford V8 side valve which was notorious for vapour lock.

Richard's advice on diaphragm removal is good, there is a knack to it. Particularly if the pump is fitted with the stem seal that prevents fuel getting into the sump in event of diaphragm failure. I find that if you hold the pump in both hands you can use both thumbs on the metal disc to push against the spring and also toward the pump mounting face to unhook the stem from the pull arm.

Reassembly is more tricky as the pull arm falls to the bottom, away from where you want it. I hold the pump upside down overhead. It also helps to hold the cam follower in against spring tension. You will figure it out.

David

[Little Jo]

Originally Posted by motto

I purchased a Dodge Weapons Carrier many years ago that had been fitted with an electric fuel pump wired to run whenever the ignition switch was turned on. It was a 12 volt truck so the battery was in a stowage box in the tray body and the battery lead passed through the pedal mount area as does the fuel line.

One day when I was manoeuvring the vehicle close to the house I stalled the engine and when I pushed the clutch pedal down there was a very audible arcing type noise and the amp gauge flickered wildly. I got out and lifted the bonnet to have a look and was shocked to find the battery lead had shifted and been rolled between the clutch pedal arm and the edge of the chassis which had peeled the insulation off. There were flash marks on the nearby fuel line which was a copper replacement.

If luck had been against me I could have blown a hole in the fuel line and the Auto Pulse would have worked its little heart out to feed the fire. There was a distinct possibility of loosing not only the vehicle but my house as well.

Modern vehicles with electric fuel pumps have to have them powered in such a way that they cease operating if the engine stops so as the fuel supply ceases in event of an accident.

In regards to WW2 vehicles, the original mechanical fuel pumps with hand priming are perfectly adequate if in good condition. The greatest exception to that is the Ford V8 side valve which was notorious for vapour lock.

Richard's advice on diaphragm removal is good, there is a knack to it. Particularly if the pump is fitted with the stem seal that prevents fuel getting into the sump in event of diaphragm failure. I find that if you hold the pump in both hands you can use both thumbs on the metal disc to push against the spring and also toward the pump mounting face to unhook the stem from the pull arm.

Reassembly is more tricky as the pull arm falls to the bottom, away from where you want it. I hold the pump upside down overhead. It also helps to hold the cam follower in against spring tension. You will figure it out.

David

David

A very interesting story, you were one lucky man, there certainly could have been a very serious accident. From the information and advice I have received from you guys I will definately stick to the manual fuel pump and thanks for the advice on re fitting the new diaphragm, sounds interesting. If you hear a loud clap of thunder and see a big black cloud in the sky, you will know I need help.

Cheers

Tony