Fuel pump issue

[Ziffdaddy]

Hi all. Sorry, I had to ask for help..my, new to me, 76 fj40, came with a weber and electric pump on it. I switched to a chinese knock off of the original (I know, crap shoot) and a cheap mechanical pump. The mechanical ran for a little bit..not long, before it wouldn't start anymore. I pulled the pump to find the arm snapped off it when I pushed on it. nice...
-I put another electric back on to get it running while I figure out what to do next.
-Fired right up, idles great, timing done as per fsm, pulls steady 18" vac, drops and recovers on a quick rev, but
-will not go under load without choke. Probably not vacuum leak, so I feel maybe dirty chinese carb/primary jet small, etc..
-I put an oem mechanical pump on it just an hour ago and it will not pull/push fuel to the carb.
-I pulled fuel up to the carb with my brake bleeder, just to make sure fuel was able to come through, and it did, but it still wouldn't do it on its own.
-Pulled the pump and it's fine. even pumped the arm by hand and it shot fuel out for the couple pumps worth of gas in it.
What am I missing??
I believe 76' doesn't need the spacer, right? the pump slid into place no problem without it.

 

[Ziffdaddy]

Could I be sucking air somewhere between the tank and pump that the electric was able to overcome enough to idle and rev well in nuetral? Nah, then it would be leaking gas somewhere and I don't see that...

 

[Pighead]

I believe 76' doesn't need the spacer, right? the pump slid into place no problem without it.

I believe that a '76 did not use a spacer, but it depends more on the fuel pump than the block. If the fuel pump has 2 fuel outlets, it is a later fuel pump and needs the spacer. Or so I've heard.

 

[Ziffdaddy]

I believe that a '76 did not use a spacer, but it depends more on the fuel pump than the block. If the fuel pump has 2 fuel outlets, it is a later fuel pump and needs the spacer. Or so I've heard.

I just have the inlet and outlet. I did not use a spacer. I'm going to run a line right to the pump and bypass my tank to see if it might be a tank/line from tank issue. Would that make sense? That'll also tell me if the pump works or not..
Is there any reason my cam wouldn't be activating my pump? if it installed easily with no spacer, it seems like a spacer would make it even father away and not work...right?

 

[Ziffdaddy]

OMG. I just went back out and looked closer and saw there is a freakin spacer on it already..It was a little dirty and not well lit, so i never noticed it..SOB. Ok, heading back out to see if it'll run..man, I feel stupid.. rookie mistake. damn.

 

[Pighead]

OMG. I just went back out and looked closer and saw there is a freakin spacer on it already..It was a little dirty and not well lit, so i never noticed it..SOB. Ok, heading back out to see if it'll run..man, I feel stupid.. rookie mistake. damn.

Well, you probably won't make that mistake again. I love an easy fix, and a good laugh.

 

[charliemeyer007]

I like electric fuel pumps and have run them for years. Some were big buck units that didn't work very well or last very long.

I'm a big fan of the cheap diode pumps as they last for years. They are like $10 on ebay or Amoron. Years back I built my first fuel transfer device. I have made like a dozen and given them to family and friends.

About $50 a few years ago. Switched, fused 12' power cord that connects to either battery or cig lighter, filtered, 5' draft and 20' delivery. You can reverse the hoses to harvest fuel. Will also do diesel. This is the same pump I run on both Elsie and my F150

 

[Ziffdaddy]

Well, it started back up fine...idles well, but sputters/pops at the tailpipe. still holding 18-19 vac so I'm not sure if there are any vac leaks.. If I give her a bit of throttle, she just bogs down and almost dies. I tried driving in the neighborhood and it just fell on its face with any throttle..if I slowly eased on throttle, it would slowly go a bit better. I'm guessing the chinese carb needs some attention? maybe main jet is too small?

 

[Pighead]

Well, it started back up fine...idles well, but sputters/pops at the tailpipe. still holding 18-19 vac so I'm not sure if there are any vac leaks.. If I give her a bit of throttle, she just bogs down and almost dies. I tried driving in the neighborhood and it just fell on its face with any throttle..if I slowly eased on throttle, it would slowly go a bit better. I'm guessing the chinese carb needs some attention? maybe main jet is too small?

Try advancing your timing a bit, see if it gets better

 

[charliemeyer007]

Accelerator pump isn't working correctly is my first thought when it idles fine but nearly dies if you step quickly on the gas pedal. More timing advance could help too.

 

[Ziffdaddy]

Sounds good. I’ll check the accel pump and add a little adv back in. Thanks, guys. I enjoy working on it, but I need to get back to my paying clients soon!

 

[Ziffdaddy]

Looking down the barrel, it appears the AP is firing a shot in there..:-/. I’m gonna pull the carb and strip it down..maybe a slight blockage somewhere..

 

[Pighead]

I’m gonna pull the carb and strip it down..maybe a slight blockage somewhere..

Did you try advancing the timing? It's a lot easier than that carb stuff and sometimes works wonders.

 

[Ziffdaddy]

Did you try advancing the timing? It's a lot easier than that carb stuff and sometimes works wonders.

I did advance it before my last neighborhood run. It did help a little, but something bigger seems to be affecting the performance. It flops when I give it gas, but if I go slowly, it’ll let it speed up, albeit, still weak.. does that seem like a carb issue? Or maybe the coil? Dist? I’m gonna check the vac advance on the dist tomorrow, too.

 

[Ziffdaddy]

I used my drill kit to determine jet sizes and looks like my main and secondary are both smaller than the SOR jet chart for my year. Should I open them up to spec or a bit more? Maybe that’s a stumble off idle reason? Accel pump seems to be functioning properly. Carb is apart and passages blown out..
What about slow jets?

 

[FJmaine]

Have you checked your fuel filter? Are there any restrictions in the line? Are you getting good fuel flow?

 

[Pighead]

I used my drill kit to determine jet sizes and looks like my main and secondary are both smaller than the SOR jet chart for my year. Should I open them up to spec or a bit more? Maybe that’s a stumble off idle reason? Accel pump seems to be functioning properly. Carb is apart and passages blown out..
What about slow jets?

If the carb is apart I'd soak it while you order a couple carb rebuild kits. They usually come with more jets. Watch the Pinhead youtube videos and follow along in your FSM (or similar). I would not start drilling jets, they're hard to un-drill. Put the carb back together as close to right as you can and see if that helps. There are a lot of different causes for a stumble off of idle, rarely have I seen it be due to jets too small. Maybe put in backwards though (secondary in the primary hole for instance).
I would look more at your ignition, specifically your timing. Yes, check the dizzy advance diaphragm but also the mechanical advance. What is your timing set at now?

 

[Ziffdaddy]

If the carb is apart I'd soak it while you order a couple carb rebuild kits. They usually come with more jets. Watch the Pinhead youtube videos and follow along in your FSM (or similar). I would not start drilling jets, they're hard to un-drill. Put the carb back together as close to right as you can and see if that helps. There are a lot of different causes for a stumble off of idle, rarely have I seen it be due to jets too small. Maybe put in backwards though (secondary in the primary hole for instance).
I would look more at your ignition, specifically your timing. Yes, check the dizzy advance diaphragm but also the mechanical advance. What is your timing set at now?

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Solid info! Yeah, the carb is actually new, but one of those Amazon ones..I stripped it down and went through it all. I’ve rebuilt a few dozen carbs over the last couple decades, so I’m not too shy with messing around a bit..…I did drill the main a minuscule amount to match it to the SOR jet size list. It’s actually running pretty solid now! I also straightened the accel pump arm a tiny bit to activate it earlier, and that seems to have helped, too. Timing set to stock, then I dipped in a little more advance.
The only thing left is that it pops a little out of the exhaust at idle.
I’m just so happy to be driving around in it! It’s been so long since I’ve had a 40, I’ve gotta get used to these things again. Love it!!
I also cut out the sill and welded in all new metal back there..gonna be a slow journey to new paint..lol.
Thanks for all the help, guys! I’ve missed this site. Good people.