Low flow thru fuel filter

[3wheelingCJ]

One day the jeep started to die after running for awhile. After messing around with idle speed and just looking around, figured out that it dies after choke was fully open and if idle set below 1200rpm. After looking around some more, noticed that there is a visible dripping of gas from driver side ventury, while pessanger side was bone dry.
took apart the carb and cleaned it out. Gaskets were also replaced. Plus new clear plastic fuel filter.
Jeep started up good and kept running at 800rpm idle. However, once the rpm dropped to 800rpm the amount of gas going thru the filter seemed very low, and didn't change as engine was rev'd up.
I took a few videos, but unfortunately can't upload mp4 on this website.

Any suggestions on how to upload the video are apreciated.

And any suggestions on how to verify that there is enough gas going to carb.

 

[007]

You could put an in-line fuel pressure gauge on it to see, but it kinda sounds like a possible fuel pump issue OR something between the carb and the tank restricting flow.

 

[Lumpy Grits]

If the Jeep runs good. Don't worry about it.
Sure hope that plastic filter isn't close to the exhaust manifold.......
LG

 

[Hedgehog]

Okay, you say it's running well at idol now. You haven't mentioned how it's running at speed. If it's running at idol and at speed then what is the worry?

How did you determine there isn't much fuel flow? Really, once the float bowl is full there shouldn't be much fuel flow, if there was at idol then you've got another problem somewhere.

 

[3wheelingCJ]

It doesnt ran good under load. Not much power, looses oil pressure, hesitates. I didn't check for vacuum leaks last night as it was getting late.
Just want to eliminate one problem before diving into the next one.

I dont have a scientific way of determining fuel flow. Just noticed that agter running for about 20min or so it went from a staedy stream that filled up the whole filter to a steady drip. The full bowl explanation makes sense.

Thinking about adding pressure gauge and regulator as well.

 

[Lumpy Grits]

Oil pressure drops with engine rpm.
What weight oil are you running in the engine?
Sounds like the carb is flooding out............
Remove the gas cap and see if there's any change.
LG

 

[Torxhead]

Oil pressure drops with engine rpm.
What weight oil are you running in the engine?
Sounds like the carb is flooding out............
Remove the gas cap and see if there's any change.
LG

When you remove that gas cap after it has been running awhile, listen for any hissing noise indicating poor venting in the gas tank.

 

[Hedgehog]

Did the problem just suddenly crop up, did it slowly start having problems or has it been running poorly for a long time?

 

[mstar]

The standard way to test for fuel pressure and fuel volume is to disconnect fuel line and hookup pressure gauge,start engine and observe pressure.Next disconnect pressure gauge and attach hose to fuel line,then with a container (metal coffee can works great) at hand have someone start engine and observe fuel flow.The pressure and volume specifications can be found in the service manual or any tune up guide.Looking at the fuel filter won't tell you anything about your fuel supply.This is for carb. applications only.

 

[3wheelingCJ]

The issue came out of nowhere. Jeep was running fine, then started to have some issues that looked like vacuum leak. Figured out break booster was the problem and replaced. Took it out on the test drive down my street and everything was fine. Left it running in the driveway to go inside to clean up quick and was going to ran some errands. It died by the time i came back out.

 

[Lumpy Grits]

Disco the v'line from the booster and see what happens.
LG

 

[Hedgehog]

Sounds like it possibly needs a new fuel pump.

 

[3wheelingCJ]

Apologies for not replying sooner. It have been raining none stop here and I don't have a garage.
So, at one point during different tests the engine died and the carb filled up with gas. It was old and I didn't trust it and replaced it.
Jeep started up fine and ran well at about 1.5k rpm. Checked for vacuum leaks with carb cleaner, including around break booster connection and everything seemed good.
The flow thru the filter looked steady and uniformed. The problems began when I lowered idle speed. It does ok down to about 1k, but sometimes the filter looked dried out and the engine started to sound like it might ran out of gas. Then suddenly bunch of fuel rushes thru the filter, rpms pick up just a touch and everything settles to a steady rumble.
This issue repeats every so often and worsens as idle speed adjusted lower. At 800, it doesn't really run.
so, is it a fuel pump? It's pretty new, but things can happen.

 

[Lumpy Grits]

Normal for the small carb on our Jeep engines.
LG

 

[3wheelingCJ]

It's a 600cfm carb and I had idle down to 700-800rpm before starting to experience current issues. Idled just fine and steady.

 

[Torxhead]

That idle does sound a bit high still, ignition timing can be a factor here. Refer to post#9, I like to just use a pressure gauge though, reading around 4-5 p.s.i.

 

[3wheelingCJ]

Yup, pressure gauge is the next step. Got the regulator from eBay and going to buy a gauge at a local store. Speaking of that, regulator has one input and two outputs. My plan is use one of the outputs for the gauge. Any issues with that?
timing should be good. I set it at about 7deg (slightly longer duration and lift cam) a couple months ago and was happy with the results thruout the power band.
Probably a good idea to recheck, but also I thought that timing should be set at 700 rpm idle which I can't get to now.

 

[Lumpy Grits]

How does the engine run on the road?
Do 'fix' somedangthing that ain't broke.
LG

 

[3wheelingCJ]

Finally got a break from the rain.
Got edelbrock carb fuel line adapter with gauge port, pressure regulator, filter and fuel pump installed.
Reading steady 6psi, but couldn't run for a long time due to a fuel leak. All connections are dry, except for regulator input port. Re applied plumbers tape (correct direction) and have a worm clamp pretty tight on the barb fitting. Keeps leaking thru the hose connection as if there is too much pressure and not enough of the path. Basically dead heading, but still got 6psi downstream from output.
the fuel pump is from autozone based on make, model, etc.

Next step is to bypass regulator, straight to carb adapter. Ran out of fuel line after cutting and replacing.

 

[3wheelingCJ]

So, I was able to fix all leaks without the need to bypass the fuel regulator. Adjusted idle to 1k and fuel pressure just under 6psi. I realize that idle should be around 700-800rpm, but the engine starts to ran rough any lower than 1k. Since I'm not 100% certain in the accuracy of the cheap o tach, figured I'm good. For fuel pressure, edelbrock calls for 5.5 to 6, again questionable accuracy of the gausge, so called that good as well.
Everything was running well on the driveway and on test runs, so went to get new tires that have been sitting in the shop for two months now (look out for a tire thread, as i might have over done it a touch).
After 30min. of city driving the idle jumped up to 1200 for a little bit, but then went back to 1k after 5min. On the way home however, after another 30min of city driving, idle started to dip down a little after sitting on the light and come back up, basically the faint ghost of the old symptoms appeared.
Opened up the hood once I got home, and with idle back up at 1200 (instead of 1k) started to watch the pressure gauge. Didn't take long to see that the pressure dips .1psi or so every 2-3sec. The dip is not big, but extremely consistent every 2.5 sec. or so (didn't take out a stop watch).

So, from what I can tell there are two symptoms that are likely related, one idle that will not stay put, and the second the fuel pressure that also doesn't stay put.

As always, any suggestions will be greatly appreciated.