clark-camp

Well, my mechanical fuel pump crapped out on me and I need a new one. Should I get a direct replacement or get an electric one?

83

I like the mechanical pumps. They rarely fail, and they're cheap & easy to replace, and easy to fix on the trail or out on the side of the road if they do fail...

But that's just me.

Team420

X2... Mechanical is the way to stay!

ConSeann3ry

whatever is easier and cheaper, they both do the same thing imho

clark-camp

Originally, I thought the Fuel Pump went bad because the carb float bowl was empty and I made sure the float was not stuck. I took the pump off and tested it and the fuel pump seemed to be working perfectly. I manually filled the float bowl and hooked everything up. The engine started right up, i gave it some throttle and watched through the sight glass as the gas level went down until the engine cut off (about 45 seconds at idle)

Upon further research, I found out it is possibly because the eliptical on the cam shaft is worn down causing the pump to not reach its full output. Before I tear the engine apart, do any of you have any suggestions?

I am going to take the top off the carb and closely inspect the float bowl and fuel intake to make sure that the problem isn't coming from that area before I try the cam shaft thing.

clark-camp

new eccentric:

http://www.lceperformance.com/Fuel-P...-p/1081026.htm

83pingpong

If it is the eccentric ring, that means removing the cam gear, which means major surgery. Why not use electric until next time you need to change timing chain?

Something like an Airtex E8251 low pressure pump should work. It would save many hours of labor. If your chain or tensioner needs replacement, you may as well go with the eccentric lobe ring. But if you need the truck running ASAP, go electric. Next time you are in there, replace the eccentric, and it will be ready to go if you ever need to.


Good luck!

clark-camp

Ok, well, I guess I'm back to getting an electric fuel pump.

If I use the one that you suggested, how do I go about hooking up the return line?

The mechanical fuel pump I bought:
http://www.oreillyauto.com/site/c/de...9&keyword=1320

suncomb1

Buy a Mallory 110 electric pump and a Mallory return type (3 Port) pressure regulator. Mount the pressure regulator downstream of the Outlet of the electric fuel pump. Install the electric fuel pump Outlet supply line, the fuel return line and the line to the carb into the pressure regulator as per instructions. Connect the fuel tank carb supply line to the inlet a large inline fuel filter and connect a line from the outlet of the inline fuel filter to the electric fuel pump inlet. Find a wire or circuit that is hot only when the ignition system is on and install a wire to the + coil of a relay. Install a ground wire on the relay coil -, connect a hot wire to the battery then to an inline fuse / fuse block and then connect a wire to the Common terminal on the relay. Connect a wire to the NO terminal on the relay and run a wire to the power / hot wire on the electric fuel pump, Connect a ground wire to the other wire on the electric fuel pump. turn on the ignition, listen to the pump run, start the motor and adjust the fuel pressure regulator. Use a minimum of size 14 gage stranded electric wire on all electrical wiring.

83pingpong

What he said. He is speaking from experience. I still think the low pressure Airtek would work fine, even without a regulator (and much cheaper!). He is right. I am probably wrong.

clark-camp

looking at the mallory electric pumps and regulators online, it seems that I would be paying at least a couple hundred bucks. I don't really have that kinda money and at any rate, I'd rather buy a $15 eccentric and put more effort into it. If I hooked the low pressure electric pump up before the mechanical fuel pump, would that work? I figure that would allow me to use the existing fuel return.

Thanks for your input! I really wish I had the money to do it right... oh well...

83

I don't know how to test it, but I wouldn't just assume the lobe is worn. These trucks go hudreds of thousands of miles without that happening. Take off the valve cover and take a look. Compare it to a good one. I'm sure it can happen, but I'd be surprised if that's your problem.

Could be, though.

Gov't Mule

I'd stay mech. I have used many elec over the years...everything from expensive Mallory from LCE (which was a total POS, btw) to cheaper Napa and Advance ones and EVERY one at one time or another has let me down! But never my mechanical. And Weber people say that you MUST run an electric with their 32/36 carbs and I've proven that to be BS as well. Been running both my trucks with 32/36s and stock mech pumps for years now with no issues.

clark-camp

I took the fuel pump off and felt the lobe inside. It was noticeably concave where the pump arm was.

clark-camp

Can I see the eccentric from just taking the valve cover off? I was under the impression I would have to take the whole head off...

Edit: actually, now that I think about it, you are probably right. I mean, the pump is right there at the valve cover.

83

The lobe is "off center". That way when the cam rotates, the lobe has, essentially, a "high side" and "low side", even though I think it's perfectly round. Since it's bolted on off center, it can move the pump arm up & down. Anyway, yeah, take a look at it and see. It could be that something happened to it, but I'd check it out first. Hard to tell by feeling around blindly, especially if you don't even know what it's supposed to look like in the first place.

clark-camp

based on the picture of the eccentric that I posted earlier, I had a pretty good idea of what it should look like. It was definately worn where the pump arm contacts it, but...

It was the carb all along.

When I first noticed that the bowl wasn't filling up with fuel, I assumed it was the pump because I had just rebuilt the carburetor a couple months ago. Before I went and bought the new fuel pump I took the sight glass off the carb and made sure that the float wasn't stuck. Today I ended up taking the whole top off of the carb, took the float assembly and the valve that is controlled by the float apart and put it all back together. I didnt see anything suspicious, but when I had the carb back together, everything was working just fine. Problem solved...

The valve wasn't stuck nor was there any foreign material blocking the valve (to my knowledge) but when I reassembled everthing, it worked fine.

Thanks everyone for sharing your knowledge and input!

She LIVES!!!

83

Awesome! Good to hear.

Ok. I never saw any photos, so I didn't realize you had looked at it.

clark-camp

THANKS GUYS!

trevorthetrekker

When I installed my rebuilt 22R, they didn't install the fuel pump eccentric on the cam; instead they gave me a spacer, like they were assuming I would be voiding the mechanical fuel pump. The eccentric is actually in front of the cam timing gear, so you don't need to mess with the chain or gear at all. In under 30 minutes I had the valve cover off, took off the cam bolt, installed the fuel pump eccentric, torqued the bolt, valve cover back on, and fuel pump on.

If you're looking to save time and money, just stick with mechanical.

If you want a redundant system (which I plan to do), run an electric pump in parallel with the mechanical pump; preferably with check valves downstream of both pumps, so all the pressure is being forced to the carburetor. Also I would highly recommend a fuel pressure regulator with the electric fuel pump, unless there is one built in.

The electric fuel pump is also very nice for priming your engine if you have a carburetor, especially if you have a Weber, since the bowls tend to try out super quick. Currently with a Weber 38 and only a mechanical fuel pump, I need to pump the accelerator a few times, which really doesn't do much with the mechanical pump and pressure regulator; at least it creates a vacuum to help it a tiny bit. This is really not good for the accelerator pump since it is most likely dry. Having the electric pump allows you to prime it without beating up your accelerator pump.

If you want to go super redundant, run a new, separate line from the new electric pump to the gas tank. Or a second gas tank. This allows you to still get fuel flow if your old line gets clogged, which I ran into since the Trekker sat for 6 or so years before I got my hands on it. I'll probably end up installing all new lines sometime in the future.

Kinda went off on a tangent there, sorry!