Mech. Fuel Pump Woes!! Its a Trickler!!!

[Tdatsun1971]

I have a 71 521 w 1600 motor. It has a weber 32/36 carb. New fuel lines, drained tank with new filters. No lines clogged.

The carb only gets enough gas to stay runnning at idle at best. Give it any gas and it is starving the carb. I have a clear fuel filter before the carb. It is just trickling in at best or not at all. Well thought it might be the pump. Bought new-nope same damn thing!!!! Could i have a worn cam lobe for the pump to ride on????? I have heard of this problem. I might try a Electric pump. Any ideas guys? This thing is going to drive me nuts!!!!!

[Jayden71]

I have a 71 521 w 1600 motor. It has a weber 32/36 carb. New fuel lines, drained tank with new filters. No lines clogged.

The carb only gets enough gas to stay runnning at idle at best. Give it any gas and it is starving the carb. I have a clear fuel filter before the carb. It is just trickling in at best or not at all. Well thought it might be the pump. Bought new-nope same damn thing!!!! Could i have a worn cam lobe for the pump to ride on????? I have heard of this problem. I might try a Electric pump. Any ideas guys? This thing is going to drive me nuts!!!!!

 

Is the carb all cleaned out from the old gas?? I don't know a lot about Webers but my stock carb was kinda doin the same thing. My 521 sat for 2 years and the jets got plugged from the crap in the gas tank. I took carb apart and had to clean everything, needle valve and jets. I now run two fuel filters just to be safe

[Tdatsun1971]

The Weber is brand new. I also run 2 filters. The stock white one[new] on firewall. And the clear one[new] before the carb.

[yello620]

sounds more like a restriction in the supply line to the pump. Try installing a fuel pressure/vacuum guage in the line between the pump and the tank. If the pump is trying to suck and it just cant get enough fluid it generally will try to suck a vacuum.

[72wagun]

sounds more like a restriction in the supply line to the pump. Try installing a fuel pressure/vacuum guage in the line between the pump and the tank. If the pump is trying to suck and it just cant get enough fluid it generally will try to suck a vacuum.

 

I did something similar to this. I installed a cheap fuel pressure gauge between my pump and carb. I got it at Schucks for about $10, and it measures from 0-10 lb of pressure. Mine read right at about 2.75 lb which is about perfect for a weber from what I've read. If you get about the same, your problem is at the carb. If not, your problem is most likely in your line since your pump is new.

 

Edit: Just reread your post, and noticed you have a clear filter going to your carb. If it's just trickling there, and you have a new carb, it seems unlikely that your problem is there. Another quick thing you could do to see if you pump is working, is to put a piece of fuel line on the intake of your pump, and stick it in a can of gas. Sounds like the line from your tank must be partially blocked though.

Edited July 11, 2009 by 72wagun

[420n620]

see if you can blow back into the gas tank before the fuel filter and see if if has any resistance, might be just plugged.

 

I wouldn't use a air hose because their might be a sock filter inside the gas tank and you wouldn't want to damage it. I just am not sure if their is a sock in there but just in case there is.. .

[ggzilla]

Pressure is irrelevant if it is a trickle. It might be a high-pressure trickle. You also need volume.

 

Sound like you havent done fuel pump volume test? Don't guess. Put a hose on the fuel pump output line to a liter can. Run the engine of the gas in the carb bowl. In 60 seconds it should put out 450 cc or more. If this is in spec, you don't have a trickle problem.

[banzai510(hainz)]

time it with a light first. if was running fine before this then timming is not the proplem.

 

I had a main jet clogg up once. off of idle it would bog out. found a tiny rock in main fuel jet .

 

if still points ignition maybe a bad condensor????????

 

at idle these car use very little gas. it takes forever it seems like to run them out of gas in the float bowl

[datzenmike]

Trickle is all you need!!!!! The fuel you see is is the fuel being used, which at idle is next to nothing. Do not expect the same flow as a garden hose.

 

Take the hose off the carb side of the pump and crank it once. Be ready ... gas will spray out everywhere!!! Pump is good.

 

Your carb jet is wrong size or plugged up.

[banzai510(hainz)]

One thing I forgot is when I went o SRSANDS place to work on his510 hehad the same issue of car bogs out above idle.

I put my carb on and it worked great. Shawn took apart his DGV and it looked OK.

Then I went to tighten the 12 mm hex nut in back of the linkae of the carb then the same thing happened. MY DGV I put on there bogged out above idle.

 

Going by the hex nuts he had holding the carb down were so tight that I said WHO GORILLAd the nut on here. I siad these dont have to be that tight. So maybe he tighten the nex nut in back of the carb where the linkage went on.

I said One should hold it open with your finger the throttle plate and jsut put it on snug and use the thin washer that come with it carb that has the tab to keep the hex nut from comming OFF.

But he did not have one so I tighten the hex nut with the throttle plate closed. Well guess what happed the carb did the same thing and the carb bogged ouyt above idle. So I took some tension off if it and it was OK. So maybe people tighten these thing too much and shoul put the carb linkgae on just loose enought before strt up and run it to rule out bending the throttle plate/shaft.

[bonvo]

i didnt see this mentioned but is the spacer between the fuel pump and the head in place?

[Tdatsun1971]

Yep, Spacer in place. Did a volume test on pump it pumps right at factory specs. Replaced wires, Cleaned Carb, Re-set timing. Set Points again! It will idle & start perfect. BUT! off idle it wants to bog down or hesitate pretty bad. Could be the condensor or fouled plugs. maybe try a hotter plug! They are getting sooty black. Man I think i picked the WRONG project, Thanks Guys, troy

[ggzilla]

My guess is there is some particles in the carb (dirt/gunk/water/etc).

 

But first, for bogging when you give it gas, do this simple test:

1. Engine Off

2. Shine flashlight into carb

3. Move throttle slowly by hand

* You should see a constant spray into the carb. That's OK.

* If instead it dribbles or doesn't work unless you move the throttle quickly, you have a problem with the accelerator pump

[Tdatsun1971]

Here is the recent news. Replaced condensers, I was missing one. Replaced plugs. Cleaned & adjusted float. Re-timed Again! WOW its running Great!!!!! I hope it keeps this up. Thanks to Hainz for all your advice. Now i can remove back bumper and start the lowering process. Cant decide to Bag it or Static drop it............ Thanks also to any others for your thoughts. There is a bunch of good guys on here! I guess we could say like brothers, With out the fights!!!!!LOL. L8tr

[banzai510(hainz)]

Static drop it

 

static drop is FREE!!!!!!!!!!

 

take the front bump rubber stops out also. just a 12mm wrench is needed.

 

lower the front first. loosen the Jam nut on the bolt with the square end.

turn the square nut till you got it almost all the way down then tighten Jam nut,. see how much you lowered it.

 

Belltech sells 3 inch 2 deg blocks. 6202 part#

 

If you go LOWER there can be carrier bearing issues as premature wear of noise.

 

 

when possible get a electronic ignition.

Edited July 16, 2009 by banzai510(hainz)

[Tdatsun1971]

Hainz, Here is the thing i just happen to have rear sleeve bags, Compressor, 2 valves,pancake tank and the 2 needle gauges sitting, from another build. Whats a guy to do?

[banzai510(hainz)]

here is my thinking,

Just because you get a FIAT car for FREE doesnt mean you should spend thousands of dollars on it!!!!!!!!!!!!!! or trying to keep it running.

[Tdatsun1971]

Yea, This is supposed to be my CHEAP project. How low is yours? I would like to lower mine at least 4" in front. But not to sure how to Re-index the bars. I just sprayed all the suspension down with PB to let it soak the threads. The posts i have seen to index the bars is kinda misleading. I willl look more into it though. L8tr have a good one

Edited July 16, 2009 by Tdatsun1971

[banzai510(hainz)]

the 521 is ezest to drop the front to reindex 1 notch.

 

up up from to A arm and loosen the nut. right before its off while still threaded bang it with a hammer.

 

I think you have to loosen it from the anchor point where the square bolt is but youll figure it out from there.

Im sure Pac Coast or somebody elese on here knows. the 620s are a little bit different as you have to unclip the C clip.

 

the 521s you dont!!!!! If I remember right.

Me and Icehouse did his truck one notch. remember you you move it one notch you maight have to readjust the bolt max to one side then loosen it up again to get desired height.

meaning maybe turn the squaer nut in so it rasies the truck then reindex it then lower it using the square bolt.

 

 

maybe olddatsuns.com has a write up on this

http://www.bleachgarage.com/620tech_spn.html

Edited July 16, 2009 by banzai510(hainz)