Car starts but won't stay running without the choke pulled out...

[DARK AGE 53]

Here's what I've got.

The last time we ran the car was 4 weeks ago ( it was running great ), until today the car has always run fine. We have a race this weekend so I went out to the shop to get everything ready, started the car up to load it onto the trailer and it just won't stay running without the choke pulled 1/4 to 1/2 way out......even with the choke pulled it dies as soon as you give it the gas.

I've checked the,
Fuel pump.
Air cleaners.
Changed the fuel filter.
Drained the gas in the fuel cell and replaced it with gas I bought today.
Checked to see if carb joint screws were tight.
Checked Vacuum chamber covers to see if they were tight.
Changed spark plugs.

I think it's either a carb problem or a vacuum leak, anyone have any idea what might be the problem?

Thanks,
Al

[Tom Cole]

What kind of fuel was in it?

[DARK AGE 53]

Sunoco 94 high octane gas, I don't think it's the gas because I put in new gas today and it still won't idle.

[qweedqwag]

Trust me when I tell you this.....you need to pull the carbs off and clean them, I  have had this happen three times only mine would sputter and pop then die. Take the bowls off and the tops off, get some carb cleaner and spray every passage you can see.  Take out the main jet , the pilot air jets and the idle jet clean them all, make sure you drain the float bowls first so you don't get fuel all over yourself when you take the float bowls off make sure you dont get cleaner on the diaphrams. Most important keep a fire extinguisher near your work area in case something stupid happens.. this is a great link if you dont have experience at this http://web.telia.com/~u14114695/Mikuni_BS36_carbs_function.htm  or you can mail them to me and I will clean them and dyno them if you pay the shipping......what a deal, no really I will glad to help.


Mike.

[DARK AGE 53]

or you can mail them to me and I will clean them and dyno them if you pay the shipping......what a deal, no really I will glad to help.

Mike,
Really, I might just take you up on that...what state do you live in?
Thanks for the info.

[justfreaky]

Hey Al,
 Are you getting enough fuel pressure?
 Also, check the vent tube; make sure it's not clogged or blocked.
 I would venture a guess that is probably in the carbs. Mike has good suggestions for you there. Also check all the vacuum lines. Sometimes, if you have to use the choke to keep it running, it's a vacuum leak.

 Just my 2 cents worth!

 Let us know what you find out.

 Good Luck!

 Steve

[DARK AGE 53]

Hey Steve,

I'm not sure what the pressure is, what I did was disconnect the fuel line at the carbs and then turned the switch on to see how much fuel came out of the fuel line.... From what I could see there was plenty of fuel coing out. A vacuum leak is another possibility, I've looked for vacuum lines but so far I haven't seen any vacuum lines ( doesn't mean there isn't any though ).  Thanks for the suggestions.

Later,
Al

 

[justfreaky]

 If your getting good fuel flow, then pump, filter, regulator; is not the problem.
Sometimes even small cracks in vacuum lines can cause you headaches. Get out your bifocals! 
Seriously; Usually, if choke can be used to keep it running, it is an air leak of some sort. As Mike said; those small passages don't take much to restrict or block them.

 Keep Looking!

 Steve

PS
 I've seen similar problems on DCR; but never the cure> Sorry! Know that's not much help.

[gramps05]

If you are going to pull carbs apart to clean them check out this site.  http://users.erinet.com/27734/Repairs/FJ_Info/Raforth.htm

[gramps05]

Qweedqwag, any chance you could explain how you dyno the carbs. Thanks.

[justfreaky]

Al, It's been suggested to check the accelerator pump, jets, vacuum leaks. Even suggested changing out the jets (larger, 5-10) to test. Check wiring also; maybe something loose or not connected??? No definite answers for you. Still checking though.

Steve

[DARK AGE 53]

Took the carbs off today to clean them, I sprayed everything ( but not the diaphrams...thanks for that tip Mike ) and blew them off with some air. Long story short, it's running fine now. Thanks for all the suggestions, support and links.

Later,
Al

[justfreaky]

Way To Go Al!
Knew you would get it licked.

Best of Luck,

 Steve

[qweedqwag]

Al,

I figured thats what it was, it is really common when you let fuel set in the bowls for I would say 2 weeks or longer without starting the car. If I know I'm not racing for a few weeks I will go out and run the car for 2-3 minutes to get fresh fuel into the jets and bowl, if you use any of the VP fuels you would be better to pull the carbs and drain the bowls, VP seems to be very sticky and caused havoc at the track for me when I let it sit for about a month, we changed the red box and it did not work, so they guys that maintain my car replaced a set of their carbs  and it ran, but not much better so I knew it was carb related. This winter take them off clean them and wrap them in a plastic bag until spring. Make sure to keep the carb cleaner off  the diaphrams....... If anyone ever needs help cleaning you can send them to me and I'll clean and Dyno them to make sure they run. I live in Texas ya'll.

Mike.

[DARK AGE 53]

Mike,

The last race of the season is this saturday, I just might send the carbs to you after that and have you dyno them.

Al