M35 Reo "Gasser" fuel pump

[Kaiser67M715]

At the Weare military rally I started having fuel issues. One was the fuel pump failed-however that was probably a secondary issue to the initial problem-as an electric fuel pump failed to solve the first problem. I am still looking into the first problem, but the fuel pump failure still needs to be addressed. (Unhooking at the carburetor, and running a line into a clean gas filled container, it failed to pick any fuel up, even trying to gravity feed it barely wanted to pump it, luckily no fuel in oil that I've seen yet)

I am looking to replace the mechanical fuel pump with a 24v electric. Looking at the Carter P4603HD, a 4-5psi rotary vane 30+gph flow pump. I've looked at some of the solid state facet pumps, but the flow rates are pretty low (10gph) which is far to close to the minimum flow rate for the stock mechanical pump (8.25gph) for me to be comfortable using.

First question, is there a readily available fuel pump block off plate for the engine block? Initial measurements show it may be close to a big block Chevy pump, but not sure, at any rate I know the retaining bolts are much larger then any other pump I've found.

Second is for safety, is there a way to create some sort of oil pressure kill switch? I plan on running a kill switch in the cab, so I can run the carburetor dry when needed, otherwise I'm just going to run a secondary relay or solenoid hooked into the main on/off switch.

Thanks for any input, I'll try to keep up with pictures as I get it all figured out.

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[CMPPhil]

Hi

Sorry you had problems at the Rally I was the one making the annoucments over the PA asking if anybody had a pump. Now to a question about the "One was the fuel pump failed-however that was probably a secondary issue to the initial problem-as an electric fuel pump failed to solve the first problem. I am still looking into the first problem, but the fuel pump failure still needs to be addressed. (Unhooking at the carburetor, and running a line into a clean gas filled container, it failed to pick any fuel up, even trying to gravity feed it barely wanted to pump it, luckily no fuel in oil that I've seen yet)"

Was the pump that fail to pickup a used pump? If so I've experienced several times when electric fuel pumps are used and then disconnect and let stand empty, seem our modern gas with ethanol allows corrosion in the check valves. The fix I found is to prime the pump with a squeeze bulb pump and let them run fuel in a loop back into the can for a while, this seems help clean up the pumps and get them working again.

Just as aside now when I use an electric fuel pumps in storage after use I squirt clean motor oil in it, then connect the inlet and outlet with a fuel hose. I started having this problem of dry pumps not working again on my engine test stand, after they stood between engine tests.

Keep us posted on what you find. Sorry I could not be of help with a pump at the Rally but all my trucks use 6 volt pumps anyway.

Cheers Phil

 

[davidb56]

I bought a Airtex E1074 from su--mit for under 40$. they sell 6-24vdc external electric fuel pumps. as for a mechanical pump delete plate...isnt it just a piece of 1/4 flat bar with a couple holes and a gasket? should take 30 minutes to make. Murphy switch for low oil pressure shutdown, and just a toggle switch for the electric fuel pump. In the old days, the fuel pump switch was hidden to prevent theft.

 

[Kaiser67M715]

Hi

Sorry you had problems at the Rally I was the one making the annoucments over the PA asking if anybody had a pump. Now to a question about the "One was the fuel pump failed-however that was probably a secondary issue to the initial problem-as an electric fuel pump failed to solve the first problem. I am still looking into the first problem, but the fuel pump failure still needs to be addressed. (Unhooking at the carburetor, and running a line into a clean gas filled container, it failed to pick any fuel up, even trying to gravity feed it barely wanted to pump it, luckily no fuel in oil that I've seen yet)"

Was the pump that fail to pickup a used pump? If so I've experienced several times when electric fuel pumps are used and then disconnect and let stand empty, seem our modern gas with ethanol allows corrosion in the check valves. The fix I found is to prime the pump with a squeeze bulb pump and let them run fuel in a loop back into the can for a while, this seems help clean up the pumps and get them working again.

Just as aside now when I use an electric fuel pumps in storage after use I squirt clean motor oil in it, then connect the inlet and outlet with a fuel hose. I started having this problem of dry pumps not working again on my engine test stand, after they stood between engine tests.

Keep us posted on what you find. Sorry I could not be of help with a pump at the Rally but all my trucks use 6 volt pumps anyway.

Cheers Phil

No worries. Was glad for everyone who helped.

The pump that failed was the "original" rebuilt mechanical pump, it has a hand primer, further testing at home confirmed that for whatever reason the pump would not siphon fuel. I'm thinking the diaphragm tore, not the first time, but it lasted less then 2 months on the rebuild, first rebuild lasted 4 years.

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[Kaiser67M715]

I bought a Airtex E1074 from su--mit for under 40$. they sell 6-24vdc external electric fuel pumps. as for a mechanical pump delete plate...isnt it just a piece of 1/4 flat bar with a couple holes and a gasket? should take 30 minutes to make. Murphy switch for low oil pressure shutdown, and just a toggle switch for the electric fuel pump. In the old days, the fuel pump switch was hidden to prevent theft.

That pump looks like a 5-9psi pump, which would be too much for the float, I have been debating using a regulator though as more electric pumps put out more then 4 psi, especially when it needs more then a 10gph flow rate.

It's not that I couldn't make a block off plate, it's just the convenience of being able to slap one on. Although now I'm toying with the idea of some 1/2 aluminum stock, and making a fuel filter mount. I would get rid of the in tank filter, run one just before the pump, and then this one in the engine bay.

I've done fuel pressure gauges on either side of secondary filters to see the pressure drop in order to gauge filter changes. May or may not do that with this truck.

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[Kaiser67M715]

As far as I can tell now, dirty fuel filter and lines are the main culprits. I can see straight to the bottom of the fuel tank, and there is barely any sediment, the tank lining I put in still seems to be holding well.

I did fill from a couple 5 gallon jerry cans at the beginning of the year, I'm wondering if 1 or more of those have significant rust issues. The only other possibility is the fuel line rusting internally.

Now I had managed to replace the filter at the Weare show, but at that time also found the fuel pump was bad (likely failed from trying to pump through a plugged filter) I find it rather odd the second filter plugged so fast, but given the amount of crud that came through after removing the filters, I guess I can't say I'm completely surprised.

I know there is a screen in the carburetor fuel inlet, so I will give the carburetor a quick clean. There was no in tank filter-I must have never installed one, I will also not install one and opt for an external filter.

So right now I plan on draining the tank and cleaning, replace the main fuel line, clean carburetor and prep for a 24v electric pump install.

I'm attaching 2 pictures, the large coke bottle has a lot of sediment, this was after removing the fuel filter and allowing the electric fuel pump I temporarily installed to run, it "burped" several times and came out nearly black, before clearing up a little. I ran it for about 45 seconds until it really cleared up. The second smaller bottle has clear fuel, and no more sediment.

I will also add, I was running between a 1/4 and 1/3 of a tank of fuel on the last trail ride I did, which had a lot of bumps and jolts, it was only after this ride on the way back to the show that I started experiencing fuel starvation symptoms. So very likely issues starting from a dirty fuel tank.

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[SETOYOTA]

I removed the gold comet from my m108 . The engine was using a 24 volt pump and it worked fine. Free plus shipping if you want it. The motor may have a cover plate as well

 

[Kaiser67M715]

Just to keep this thread updated, I decided on the Carter P4063HD 24v, 43gph, 4.5-8psi. I may need to install a fuel regulator, but should be fine as the stock pump must put out a minimum of 5.5psi, and also needs a 10gph flow AT idle, I thought both the PSI and flow tests took place at 1,800rpms, but only the pressure is, flow is taken at the 450rpm idle.

Anyways, also got a couple toggle switches, relays, and an oil safety switch. Hopefully this weekend I can get it all installed (mostly) I do want/need to get one more toggle/push button so I can do a fuel prime, this needs to be a momentary so I don't accidently leave it on.

I plan on trying to mount the pump behind the battery box up on the frame. Right before where the fuel line enters the frame to go to the drivers side.

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[davidb56]

electric fuel pump should be mounted low and close to the tank. most people mount it on top.

 

[davidb56]

GPH= Max HP x BSFC (.5lbs fuel per HP) typical engine example = approx 230hp divided by .5 = 115lbs per hour fuel. Divided by 6 lbs per gallon is slightly under 20 gallons per hour wide open throttle. Just plug in your engine HP and do the math so theres no guessing.

 

[Kaiser67M715]

electric fuel pump should be mounted low and close to the tank. most people mount it on top.

In the proposed location it will be at 16 inches above the bottom of the tank, and will be below the maximum of 25 inches of Carter pumps recommendation. The exhaust is right on the other side of the frame rail, so mounting the pump lower puts it close to the exhaust then I would like. I am still looking into trying make it fit between the gas tank and the battery box, but space is really tight there.

GPH= Max HP x BSFC (.5lbs fuel per HP) typical engine example = approx 230hp divided by .5 = 115lbs per hour fuel. Divided by 6 lbs per gallon is slightly under 20 gallons per hour wide open throttle. Just plug in your engine HP and do the math so theres no guessing.

Assuming that works as well as it could that means I would need a 14gph minimum pump. Most of the solenoid style pumps are between 10 and 15 gph. It might have been enough, but I'd rather not worry about will it be enough, and just know I'll have the flow when needed.

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[Kaiser67M715]

I made a bracket to mount the pump to, and have it currently mounted between the battery box and fuel tank, this leaves the inlet and outlet of the fuel pump at around 8 inches from the bottom of the tank.

Because of the brackets and space I am really limited to how I could have mounted the pump. The attached picture shows the bracket I made, I may need to add another brace, but as it stands now, it is rather sturdy...

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[Kaiser67M715]

I'm going to attach a picture, that shows the wiring I will be doing. I am using the Standard PS-64 Oil pressure switch, that opens the circuit with less then 5 PSI of oil. Typical wiring has the 'S' terminal connecting to the Crank wire on the starter for a prime system, but with no Crank wire, I will be using a momentary on/off switch to prime the system. the 'I' terminal is Ignition on power, with a hidden on/off toggle. Normal relay setup. I am placing the fuel pump fuse before the relay, I've seen some debate as whether its better before or after, I figure 1 fuse would protect the relay and the pump the same as 2 separate fuses would.

If anyone sees something I should change, let me know, but the wiring should work good, with the slight added safety of an oil shut-off, and convenience of a prime.

 

[fleetmech]

Kaiser, Its a long time since you asked but, at least on later civilian Gold Comet engines, yes a big block chevy block off plate will fit, as will, interestingly enough, the electric fuel pump mounting bracket from a 98.5-2002 Cummins as found in Dodge pickups. The stock 24 valve Cummins electric fuel pump was mounted over the unused mechanical pump hole. The godawful stock electric fuel pump was long dead on my Cummins, so I blanked off the hole with a BBC cover, then re used the bracket when my 1969 Diamond Reo's mechanical pump died a few years later...