Multiple fuel pump failures

That narrow wear mark could be the cam going bad or just that the lever wasn't made properly. Suction filters have the disadvantage that pressure loss in the suction side is going to hurt performance a lot more than in the pressure side. On the other hand they do protect the filter from crud. Is the filter stopped up? If that is a metal fuel tank, which I think it is, then it is probably full of nasty stuff. How about the fuel lines?

Cheers,

Earle

Earle,

I'm also thinking the wear mark just shows the lever was not correct. The others I replaced showed wear across the lever.

The clear filter was just put on today, so stopped up was not the issue in the past. And, yes, it is a metal tank, which is what made me start thinking there might be a crud issue.

Every time I replaced the pump, I also replaced the regular fuel filter at the carb, and there has never been any debris come out of it when I pour off the fuel from the filter. I also replaced all the short pieces of rubber fuel lines connecting everything together each time.

As for the lines to and from the tank, I have not messed with them. To me, it would not make sense that they might be the trouble, just based on everything being trouble free, then sudden failure. But then, what do I know?

When it fails, fuel flow drops to near zero when I take the line off of the carb filter and turn the motor over. When it is working, I get a strong flow from the line.

Larry

Earle Hort> That narrow wear mark could be the cam going bad or just that the

Could be the pump lobe. My last chevy 305 V8 tended to wear lobes and after two pumps and one cam I went with an electric.

At this point I'd just slap on a blockoff plate and install an electric pump and pressure regulator.

...and a rollover killswitch.

oops. Guess you wouldn't need one on an injected motor.

If you don't have the correct fuel filter, with bypass back to the tank is plugged, you'll cut the eccentric cam lobe off as Doug as said. And you have another filter inside the frame rail, on the drivers side above the front half of the spring. There's a shield you have to remove to get to it. They're shown in this parts view page:

God Bless America, Bill O|||||||Omailto: snipped-for-privacy@aol.com

The fuel tank will also have short rubber hoses connecting it to the steel lines that run along the frame rails. A tiny suction leak could be the root of your problem. Metal tanks are bad news if you live in a high humidity area. I am wondering myself how long the polyethylene tanks last though. If you are retired and have time, well drop the tank and replace all the rubber that is associated with it. Then take a look inside with a flashlight. They put ethanol in the fuel now too, which might not be compatible with the fuel pump internals you are getting. I don't know what you could do about that though, except maybe switch brands of supplier.

Good luck,

Earle

problem,

Nah, your right. With any electric you should have a rollover switch, engine interlock, or at least a panic kill switch.

It failed again. After installing the new pump and clear filter yesterday, I re-started it four times, and it ran about 15 minutes.

Got in it this morning, it fired right up, and by the time I got of the garage, it died. The clear filter has no debris in it, so, at least in this case, that would not be the problem.

I wonder if NAPA has a batch of bad filters, or maybe they have been stocked so long the diaphragm has gotten old.

I have thought of dropping the tank, but back problems won't allow it. A thorough search of all lines running to/from tank show absolutly no signs of any kind of leak. No stains or smells.

I haven't seen a station around here that doesn't use a ethanol blend, so I might be out of luck on that one.

Larry

Doug-

Any idea what to look for in a lobe? Something I can see by looking at it from the outside the block? I would sure hate if that was the problem, since this re-man only has about 11,000 miles on it. Out of warrenty, though, because of the time frame involved.

I thought about the electric pump last year, but failed very little on-line that would help me with the process. This is a carbureted motor. Would it work?

Larry

Not injected.

Larry

Your Gas filter is in upside down would be my guess.

The filter has two outlets. The center one goes to the carb and the 'top' one goes to the return line. If the return line outlet isn't up top, gas siphons back to the tank when it sits air locking the pump.

If this is it, two or three primes down the carb with gas will normally get it going again.

A pinhole leak in the gas line also causes this. It is a suction line, so a small leak only makes a stain, it doesn't drip but will let air in when it sits. You didn't find a stain though, so...

Mike

Nope. Filter is correct. I found out many years ago that even if it is off by just a small amount, I have problems. Besides, I think even you would amazed at how many times you have offered up that very important piece of info that gets overlooked. I find them them to be very benificial in that it continually reminds me to get it correct!

Any kind of leak won't explain this, Mike. At least, not in a manner that makes sense to me.

Today, I talked to a friend who owns his own garage, and he convinced me to forget the NAPA and Advance Auto Parts pumps, and get a Jeep one. Provided, of course, the pump lobe is good. I'll check that tonight.

Any guesses on how rare those are?

Chrysler doesn't make/stock/provide them anymore. There are two dealers in the eastern U.S. that have them.

Depends. Some use a fuel pump pushrod and some just ride the cam lobe. The Chevy 305 1982ish had a real problem with the pump arm being harder than the lobe and wearing it down. The end result was no fuel pressure even if you put in a new pump. Been too long since I messed with a mechanical pump.

Sure. Just goes ==== pump ===> regulator ===> carb '-----return----'

Best location for an electric pump is actually back by the gas tank and low on the frame rail. (out of rocks way)

All depends on the type of electric pump.

For an electric pump a safety circuit is a good idea. Make sure it only gets power when the starter circuit is energized or the engine is actually running, not ignition is on. The documentation with the fuel pump should give some useful ideas. Some people energize them with a relay fed from the starter circuit and the oil pressure signal. You don't want to be pumping fuel if the vehicle is upside down or if the vehicle is on fire, etc.

Cheers,

Earle

The most common used to be an oil pressure interconnect.

way if the engine turns over, the oil pressure will goto zero, the pump stops, and the engine stops. Just remember to keep a jumper in case the switch dies on the trail. :)

I used to have a car that burned out starters regularly, pretty much every six months. No one could figure out why, except that there must have been an intermittent short somewhere in the electrical system. It wasn't a big deal costwise since I could get a new starter fro 20 bucks with the core exchange, but it was a hassle having to always carry a spare since I never knew when exactly it would fail.

Could there be an electrical problem somewhere that's shorting out the pump?

A YJ pump will work I believe. The inlet is just on the other side so the rubber line needs to be a bit longer to swing around.

Mike