Carb Problems! Carb Rebuild 101 please! (1 Viewer)

[Josie'sLandCruiser]

Hi All:

I have a problem! The Jim C. re-built carb that I got last Summer has apparently sucked some "crap" past the fuel filter. The problem is that the rig "stumbles" when the RPMs are higher that 2000 when under load (i.e. going uphill at speed.)

How should I clean-up this carb?

Thanks for any suggestions!

Alan

 

[Pin_Head]

The symptoms don't sould like dirt in the carb to me. If that was the case it would "stumble" more regularly. Sounds more like a fuel delivery problem and not keeping up with demand so that the bowl empties under load.

 

[Doug_S]

Hi Alan,

It's kind of a messy job, but I'd be inclined to check the output of the fuel pump. It's possible, like PinHead mentions, that your pump may not be supplying the engine's needs.

HTH

Doug

 

[cruiser88]

check the sight glass on the front of the carb it should be halfway.anotherwards on the dot.

 

[bull]

Alan before you do much of anything. Take the fuel line off before the fuel filter and blow compressed air back into the tank then drive it? Better? When it starts to stumble turn it off and check your float...is it low. I went through this exact mess. I had a clogged fuel pick up line INSIDE the tank..

How is the float level?

Then check your fuel filter

Then check your fuel pump

 

[Josie'sLandCruiser]

Hi All:

!Aye Caruba!

Bull, glad to hear that you & Kelli are home safe from the 45 Run!

This problem started-up about three weeks ago over near Rimrock Lake while driving to Naches to fuel-up. The FJ40 ran fine at low speeds, but while going 55-60 MPH it would "stumble" and "surge" like there was some crap in the fuel system. Pulled-over, changed-out the fuel filter (which was filled with "paint-like" chips and thought all was well. Had continuing problems while driving home over White Pass (had to stop twice to blow crap out of the fuel filter to get home.)

Recently, I have changed the fuel filter again, thinking the problem was delat with, and have experienced the above mentioned stalling and fuel surging.

I'm just looking for ideas to get the rig ready for the the next run!

Regards,

Alan

 

[spotcruiser]

Alan,

The same thing happened to me once, about 25 years ago, after using fuel from an old, rusty gerry can. I had to stop roughly every 10 miles between Cle Elum and Seattle to blow out the fuel filter. Did you use fuel from a can on that last trip?

You should probably drain and flush your tank and then install a new filter. While you're at it, replace that plastic tank. :^)

Todd.

 

[Josie'sLandCruiser]

Hi All:

O.K. - so I blew compressed air through the fuel back into the fuel tank this afternoon. Now the rig won't start-up!

The fuel pump (which is an aftermarket electric unit mounted on the frame below the battery tray) does work, but cannot seem to draw-in any fuel! I even tried pumping gas from a Jerry can - the pump rattles away but does not pull any fuel from the can.

Any thoughts/suggestions on this?

Thanks!

Alan

 

[CruiserMax]

Interesting thread Alan. It seems like the more learned voices on this here Mud forum point to systems below the carb as the culprit. This info more or less matches the points that Mark Whatley made the other week when we had dinner with him in Seattle. You have a good Jim C rebuilt carb. It always seemed like you have had some kind of fuel delivery problems over the years. I think Todd is right: ditch that plastic fuel tank and find another good stock tank, get it cleaned and make sure that your fuel pump is working well. Some of these same issues were around before the carb rebuild. It sounds like your tank is polluted and the "nasties" are getting sucked upstream...


Max

 

[1973Guppie]

I would: recheck the tank, if old and rusty inside replace, replace all lines if needed especially if they are old, replace fuel pump if old as they do wear out especially the electric ones, replace all fuel filters, blow the carb out, and before hooking up ensure you are getting plenty of fuel pumping up to the carb, let the fuel pump into a can before attaching to carb line, HTH, Noah

 

[mr_manny]

Similar experience here...
One day my 40 started to stumble on the freeway.
I was fine around town, but this would change the moment you headed for the on-ramp.

I replaced the Mechanical fuel-pump, and both fuel filters. Not sure if that's original or not, but my 40 was running TWO fuel filters (one before the pump, and one after). This seemed to help, but only after shooting compressed air into the fuel-line (towards the tank) did my issues go away.

Bull, X2 on the safe return...as I said before, truly a pleasure meeting you and kelli.

Will try to make it to Pismo to take you up on the Tequila Offer
manny

 

[Josie'sLandCruiser]

Hi All:

O.K. - I replaced the electric pump on my rig this afternoon with a new electric pump and the rig is running again.

The problem seems *largely* to be taken care of - I do still get some hestitation over 3,000 RPM while accelerating uphill

Any thoughts?

Thanks!

Alan

 

[65swb45]

Hesitation OVER 3k rpm could be several possible different things.

1. Fuel delivery [still]
2. Spark scatter [do a thread search if you haven't heard of this phenom]
3. Spark timing
4. Secondary in the carb

Hth

Mark A.

 

[cruiser88]

on my cruisers 40s that is i believe i had to move the fuel pump around to get it just right depending on the volume of the pump

 

[Pin_Head]

Any thoughts?


Alan

Since replacing the fuel pump had some significant effect, I thing you are on the right track with the fuel delivery. Maybe the fuel line is clogged either before of after the pump or the fuel screen at the carb inlet.

If you can, try running it and when is stumbles, shut off the ignition and coast to a stop. Check the fuel level in the bowl and if it is empty or low, this would confirm a fuel delivery problem. If, so check the volume the pump puts out in 15 seconds of running. Should be about a cup. If the output is OK, then start checking the inlet screen and line for obstructions.

 

[Josie'sLandCruiser]

Hi All:

"Cruiser88," could you please clarify what you mean by the below statement?

Thank You!

Alan

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"cruiser88" wrote:

>on my cruisers 40s that is i believe i had to move the fuel pump around to get it >just right depending on the volume of the pump

 

[Josie'sLandCruiser]

Hi All:

Thanks "Pin_Head" for the response!

Can you explain how one accesses the fuel screen at the carb inlet line?

!Mucho Gracias!

Alan

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"Pin_Head" wrote:

>Since replacing the fuel pump had some significant effect, I thing you are on the right track with the fuel delivery. Maybe the fuel line is clogged either before of after the pump or the fuel screen at the carb inlet.

>If you can, try running it and when is stumbles, shut off the ignition and coast to a stop. Check the fuel level in the bowl and if it is empty or low, this would confirm a fuel delivery problem. If, so check the volume the pump puts out in 15 seconds of running. Should be about a cup. If the output is OK, then start checking the inlet screen and line for obstructions.

 

[Pin_Head]

Can you explain how one accesses the fuel screen at the carb inlet line?

!.

The screen (if you have one) is on the end of the needle valve seat. Remove the carb top cover, remove the float and needle, unscrew the seat. While you have the cover off, check for dirt in the bowl.

 

[Josie'sLandCruiser]

Thanks "Pin_Head!"

 

[FJ40Jim]

Alan,
You've gotten many good suggestions here.

Per your email inquiry:
How to (maybe)clean a 2F carb without tearing down.
- disconnect both fuel lines.
- remove fuel inlet fitting and fuel return assembly
- remove bowl drain plugs, placing a rag underneath to catch the spilled fuel.
- using Gumout spray carb cleaner, blast in the fuel inlet and fuel return, alternating. Chase w/ compressed air where avalable. The sand & crap that is piled up at the inlet screen (visible when looking in the inlet hole), can be moved/removed by blasting back & forth w/ the carb cleaner. Also, since the float is fully dropped now, the small bits that made it through the screen will fall through the wide open needle valve, allowing it to control fuel level better when the bowl is refilled.
- using Gumout, spray in the brass vent pipes in the top of the carb throat. The gumout will wash out of the drain holes on the front of the bowl, carrying some of the loose sand & dust out of the float bowl.
- remove idle mixture needle. Spray gumout in mix screw hole, while holding throttle open, so the idle port is uncovered. Put mix screw back in all the way, back out 3.5 turns.

-Place a clean container under fuel feed line. crank engine to get a cup of fuel. By running the fuel line wide open, much more gas is flowed than normal, washing loose junk up & out of the feed line. Junk that just moved around in the line before, but couldn't really get out.

Reconnect lines & install drain plugs, see if it runs any better, check float level.

This will often make an improvement on an old FJ40 w/ dirty tank that is blocking the trail for everybody else.