Different pump arms on fuel pumps! Beware!

O

OldJoe28

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Jun 13, 2023
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Location
North East Pa
This is on my '89 YJ.
Thursday's," To Do List" was replaced the fuel pump, (one on the jeep is old looking n rusty,), new Carter Carb.
No issues with it, but, figured, New tank sending unit, new carb, might as well do old looking pump! Now fuel system is all new, no issues for long time!!!
I could only find a , "Delphi", with inlet in front, ( that's what's on there now, inlet in front).
Unbolted and pulled out. New one SLIPPED right in, ( no pushing up on pump to compress arm as you bolt it in.
" Hmmmmmm, that's weird"??????
Hook up lines, crank motor, its pushing fuel out!
Replace carb, fuel filter, and fire up. Nice!!!!!
Trip @ block, short run up highway...... Good!
Next morning fire it up, electric choke issues to iron out, but, started, head to work.
3 blocks away, dies!!!!!
No fuel in carb??!!
Take filler cap off tank, bang carb, fires up. " NOW WHAT"?????!!!!!
Run it home, hop on bike, head to work.
Yesterday,( Friday), was try to set choke, no issues with pump idling in yard????????
I noticed if I put my hand on metal line from pump to filter, I could feel a vibration like pump REALLY banging away?
" Funny don't remember old one being like that"????
This morning, for sh**** and giggles, drop pump. ( they gave me like 4 gaskets, usually I get 0)!
Yanked it out, looked at pump arms.
Old one and this one WAY different bend in arms ( see pics). I don't think this was resting on cam lobe, hence the banging vibration.
Put old one in, fired it up, no vibration at line, order another pump ( this one has inlet in rear, but, pump arm looks same in pic).
Any reason for this issue?
Is this '89 supposed to have inlet in rear of pump?
I hate replacing a part and creating problems like thus!!!!!!
This Jeep is 1 step forward, 2 back!
Joe

IMG_20230715_160327.jpg
 
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I have put two fuel pumps into my YJ....And both had to be "Crammed" In And then reapply the bolts from front to back to get it to seat into the the gasket...
It's running fine but, I'm thinking that the return discharge "Cone" Is rammed into the bottom of the tank and it's back feeding causing the pump to burn out. I found evidence of the contact butt connector under the mounting plate showing overheating. The only thing I can think of is pulling the pump and drilling relief holes into the piping leading to the discharge tip on the return.

inlantrade.com%2Febay%2FJPMMRYJRYBZC00001%2Fd513-3.jpg
 
T-Rex Jeepster said:
I have put two fuel pumps into my YJ....And both had to be "Crammed" In And then reapply the bolts from front to back to get it to seat into the the gasket...
It's running fine but, I'm thinking that the return discharge "Cone" Is rammed into the bottom of the tank and it's back feeding causing the pump to burn out. I found evidence of the contact butt connector under the mounting plate showing overheating. The only thing I can think of is pulling the pump and drilling relief holes into the piping leading to the discharge tip on the return.

View attachment 121588
Click to expand...
Well, you're posting the pic of an electrical fuel pump and the OP is posting the drawing from a mechanical fuel pump that is engine mounted and driven off a camshaft lobe.

OP, you got different gasket sets because the pump is built for different applications. I can't speak for your noise but this is the curse of dealing with older vehicles. We get a bunch of "universal" parts that sometimes we have to make fit.



T-Rex, you need to get a fuel pressure gauge and put it on your fuel rail and see what your pressures are. Otherwise, we're just guessing. That rubber tip should be "rammed" into the bottom of the tank, that helps stabilize the whole contraption in the fuel tank. In my experience, the return portion of the fuel loop is susceptible to pinching where the rubber lines run over the tank skid plate and can cause you to run the pump too hard and also experience excessive fuel pressures.
 
Yes, this is a mechanical fuel pump.
I ordered one from Extreme Terrain in the hopes it's a good match.
It was almost twice the cost, but, if it works.....
Waited with baited breath til it arrived.
Sadly, same bend in the arm!
Sent it back.
I don't know the history of this Jeep, when n where this pump came from.
I would THINK the arm has to make contact with cam through the full turn of the cam.
This looks like it'd be close to 1/4" space when it spinning, ( this is the banging I feel, again I think).
I was thinking if adding a ," spacer" to the arm, but, can't think of a permanent way to attached it to arm.
Not sure where to go, what to do.
I'm not happy if the old pump goes and I' m stuck putting an electric pump on, ( trying to keep it simple here).
Joe
 
I'm not familiar enough with the 4.2 to know what's what, but I found a thread that claimed some engines had a 5/8ths spacer between the pump and the block. Honestly, if the old one was working fine, put that back in for now. If it looks too bad for you, clean it up and maybe shoot it with some paint. Maybe take a very close look at the old pump and see if it has a spacer?

Doing some looking around on Rock Auto it looks like the DELPHI MF0096 has the same arm geometry that you traced out.

1989 JEEP WRANGLER 4.2L 258cid L6 Fuel Pump | RockAuto

RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. Easy to use parts catalog.
www.rockauto.com
 
Got it!!!!!
So, I ordered a CARTER pump from Rock Auto.
Received it today.
The arm length and bend is EXACTLY like old one.
Be careful when ordering you pump.
All 3 I ordered stated they fit my '89 4.2!
Joe
 
DOWNS said:
Well, you're posting the pic of an electrical fuel pump and the OP is posting the drawing from a mechanical fuel pump that is engine mounted and driven off a camshaft lobe.

OP, you got different gasket sets because the pump is built for different applications. I can't speak for your noise but this is the curse of dealing with older vehicles. We get a bunch of "universal" parts that sometimes we have to make fit.



T-Rex, you need to get a fuel pressure gauge and put it on your fuel rail and see what your pressures are. Otherwise, we're just guessing. That rubber tip should be "rammed" into the bottom of the tank, that helps stabilize the whole contraption in the fuel tank. In my experience, the return portion of the fuel loop is susceptible to pinching where the rubber lines run over the tank skid plate and can cause you to run the pump too hard and also experience excessive fuel pressures.
Click to expand...
I dig what you're saying about the stability by driving the pump down into the bottom of the tank...But the discharge/return is torqued down into the bottom of the tank blocking the flow from the return...See the tip of the black cone? The pickup is drawing off the side through the sock/filter...I'm thinking that the higher pressure on the return is bogging down the pump.

nlantrade.com%2Febay%2FJPMMRYJRYBZC00001%2Fd513-10.jpg
 
Again. That's meant to be like that. Yes the "black cone" is your return. Are you for sure seeing excess pressures? If so try something before pulling your hair out, dropping the tank multiple times. Unbolt the front of the tank skid and drop it down like 1/4 inch and see if your excess pressure issue is fixed.
 
Up date on Carter pump I installed in my '89 YJ.
The '88 Carter carb developed a " drip, drip, drip" not too long after installing of the pump.
First I thought the NEW Carter carb, ( from a '88 4.2), from Amazon was dog crap, I'd have to pull the top and check needle n seat or adjust float, or both.
Then I thought," didn't do this UNTIL I installed new pump"??
Went to parts store and got a ," Mr. Gasket" pressure regulator.
Installed it and set at 3 on scale of 1-5.
Cured drip, drip, drip!
Took it to work next morning, got to work and noticed pump dribbling fuel out vent hole in pump!
I'm thinking it was too much, " back pressure", ( even though it has the bypass on the filter). The regulator was installed AFTER the filter, just before the carb.
I looked on line about pump PSI, it was quite a bit max??!! minimum PSI is 7 .
Older pumps have a minimum of 2 PSI.
I'm hoping the pump was dog crap, the one made Friday, just before shift shut down!
I ordered another one, but before I install it, I'm going to make sure return lines from the filter is in working order and it is dumping fuel back into the tank.
I am going to do a PSI test on new pump at different RPM, to see what kinda pressures it makes.
The saga continues!
Joe
If it all went smooth, what fun would that be???
 
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