having issue with too high of idle?

[danyboy]

hello again, 94 Merc. 3.0LX alpha 1 gen.2.... my next issue (now that i got the cutting,bogging,dieing out issue resolved, which was the fuel pump)now its that I'm idling way to high (at about 1,600 rpm) but when i try idling her down to be where she should be ( 650-700 ) she will die way before she gets to the 700 mark,she dies at around 1100-1000, so is my timing out maybee??she does not get hot or overheat( if anything she runs to cool i think, gauge never goes over 150,stays at around 130-140 for the most part ) and there is no water in the engine oil (so blocks fine,no cracks.) so is my timing retarded to much maybee??( i know they will run hot when timing to advanced,but dont know if they will run to cool when retarded??) or do yall think it might be the carbie? just looking to cover all angles,I dont have a timing light to check the timing but i can shure get one if yall think that might be the issue? also i was going to rebuild the carbie anyway( been about 4 years) any other ideas??? thanks in advance for any input......danyboy

 

[danyboy]

Re: having issue with too high of idle?

Also i just bought a ACTRON INDUCTIVE TIMING LIGHT ( auto-zone $42.95) will this one work for setting my timing?? or do i need the digital display light that cost $120.95??? just wandering before i open the package-up?? thanks.

 

[chaparall villain 2]

Re: having issue with too high of idle?

yes that timing light should work fine .... on the idle had you removed the carb or just the pump ... it sounds like could be slug that made its way into carb or a vacuum leak but if you didnt have the carb off i dont know ... i would check the timing but its gonna be hard with it idling that high .... it is supposed to be checked around 650 rpms good luck

 

[Quadruplecccc]

Re: having issue with too high of idle?

sounds like an intake leak. Try spraying carb cleaner around intake gaskets and around carb gaskets while its running and see if you get an idle change , This will show you if you have a leak or not.

 

[bigdan1]

Re: having issue with too high of idle?

if you have 1600 rpm idle it means that you had to screw the idle speed screw in a lot ....

put your hand partialy over the carb to obstruct the air in ...if engine dies no leak !

definitely that you must have done more then just switch fuel pump to have that high idle

 

[Don S]

Re: having issue with too high of idle?

Disconnect the throttle cable from the carb linkage and see if it will idle down. You may have to adjust the cable barrel to SLIGHTLY preload the carb linkage to the idle position.

 

[danyboy]

Re: having issue with too high of idle?

thanks guys,i will try all the above,(1.) first i will check for vacume leaks...( bigdan 1 i like the idea of covering carbie opening to check for leaks) (2.) then i will do what DON S. suggest to do with linkage on carb.( wow Don you have helped a *@!!! load of people on this site!!!!!! way cool!!!! I will try all the above today and post back results a.s.a.p. thanks a million again to all for your advice. Danny.

 

[Cuyose]

Re: having issue with too high of idle?

I had the same issue for a while bringing an old 5.0 back to life. My issue was a few things. Maybe you can check these too.

1)Definitely check the timing. If that is your issue an easy check would to bring it back to idle where it almost wants to die. Loosen the distributor bolt and rotate distributor slightly clockwise and counter clockwise. If you get an advance in rpm, keep lowering the rpm and use the timing light to dial it in to 8 or 10 degrees advance at 650-700 RPM, whatever your engine calls for.

2)Check and make sure choke isn't stuck.

3)It really sounds like you have a blockage in your idle circuit in the carb(if you don't have any vacuum leaks) Order a carb rebuild kit, they are relatively cheap and rebuild carb. Since taking apart a carb and putting it back together and tuning can be a pain, I would do this last after you have followed all the other troubleshooting tips.

Good Luck!

 

[danyboy]

Re: having issue with too high of idle?

ok here is the latest, (1) dont think i have vacume leaks, i sprayed the intake area and rpm did not change,also i put my hand over the carb and it died fast(after almost trying to suck my hand down the carb throat WOW!!) (2) DON S you were right on the money with the throttle cable!! i removed the throttle barrel and readjusted it and brought idle way down,also before this adjustment my shifter was very stiff(up front)going into neutral,drive,reverse(now its smooth as butter) and my carb butterfly was stuck in the open position,and after cable adjustment i could freely flap it back and forth.... (3) i checked my timming following don s instructions in the stickeis by putting in base timming,it was on 0 degrees so i just slightly moved dist.so it read 2 deg BTDC (but she seemed to idle a little worse?)pulled jumper on dist.and reconected switch wires and checked again read about 13 degrees BTDC, but when i killed engine it dieseled once,So i repeted steps and moved it back to 0 degrees base,and 11 degrees BTDC out of base timming,and when i killed engine it did not diesel( and started faster also) so i guess i will leave it set there....engine still seems to have a slight miss though(with rpms down engine shakes a little) Im starting to think my rpm gauge is bad or somthing because it fluxuates and will drop down then back up and when i turn engine off it moves down very slow and somtimes stays at 1000 mark and somtimes not,also on the water when it reads 4800 i can still nail the throttle more and go alot faster sending her in the 5000+ and i dont remember it doing that before (it was always at 4800 maxed out before??) so i think i need to check into that also, anyways of testing rpm gauge??? thanks to all you commrades for the help

 

[Don S]

Re: having issue with too high of idle?

Have you adjusted the idle mixture to see if the idle will smooth out.
I see lots of 3.0L engines that are adjusted to lean which causes rough idling and dieseling.
MANY DIYers seem to think that the idle mixture screw setting shown in the manual is where it needs to be. But it's nothing more than a preliminary adjustment to get the engine running, so the timing, mixture and idle speed can all be set at the same time, and readjusted till each setting works with the others.

 

[bigskiohio]

Re: having issue with too high of idle?

You may have to adjust the cable barrel to SLIGHTLY preload the carb linkage to the idle position.

I had to do this to mine