butters8435

Hi.
I got a 1986 transam lg4 305 CCC.When I got the car it ran good.I decided to do a full tune up with delco plugs(r45ts) and delco wires blue streak cap and rotor.I also installed an open element air cleaner.I went to take it for a ride afterward and it would not start.Spark was good fuel flow volume to carb was good so I dissasembeled the carb and found the needle had come appart and was clogging the seat(rubber end came out of the aluminum part).So I went out and got a carb kit and rebuilt the carb.Only setting I changed was the float highth because it was way to low with the new needle and seat.I took it for a ride and it runs good when cold after it warms up and the cooling fan comes on it starts intermittently missing at idle and hesitates on acceleration.I adjusted the idle air bleed with a dwell meter to 30 o2 sensor is working normally canister purge is working properly ignition timing was slightly advanced (2 degrees spec is 0 ) so i retarded the timing and it ran worse.If i advance the timing to 4 degrees it seems to run like a bear with a slight hesitation when hot.I am setting it according to the instuctions under the hood disconnect the 4 wire est and set base timing.I pulled the carb and rebuilt it again and checked all the settings with the proper tools for rebuilding ccc carbs the accelerator pump is working properly the tps is working normally the map has good vacume to it and is working properly.I reinstalled the factory air cleaner for a day and it still ran the sam hesitaion off idle.I did some visual inspections and the only stange things I found are the distibutor shaft has about 3/16 of and inch of endplay(up and down) no side to side play.and the fuel pump return line hose looked kinked so i pulled it off and it is a molded hose not kinked but the return line on the fuel pump was leaking alot of fuel out of the pump with the line off and engine off.I cant seem to find any specs on distibutor end play.It seems excessive to me.COuld this cause and off idle hesitation?Also I cant find any information on the return line on the fuel pump.Is it normal for it to leak gas out of the fuel pump with the line off and engine off?When I shut the car off hot I can hear fuel boiling in the fuel feed line to the carb.Could the fuel pump be bad causing this?I'm stumped with this hesitation.I have been messing with the car for over a month and am no closer to repairing it.I hate guessing and replacing parts because that gets expensive.But im running out of things to check.Any ideas??

Vader

Good information.

As for the distributor, obviously, no end play would be best. However, if you're thinking that the end play may be causing reluctor/pickup clearance variation, the normal rotation of the camshaft and distributor tends to pull the distributor shaft downward to keep the oil pump shaft engaged. Even with a loose timing chain, the oil pump load tends to cancel the lash at the distributor gears, so there is no pulsation or variation of the load.

Are you sure the float is set correctly? even though you're higher, the symptoms you describe sound like a lean/hot situation.

butters8435

Yes the float is now set at spec.11/32 is what is called for in the factory service manual and the carb rebuild sheet that came with the kit.The first time I rebuilt it I set it 2/32 higher to allow more fuel into the float bowl (I usually do this a little richer usually never hurts(usually))But when I had the drivability problem the second time I rebuilt it I set it to its proper spec. So I think the lean condition due to a low float is not the problem.THanks for the info on the end play.I guess i'll keep looking for other stuff if thats the case.Funny thing is when setting the timing it appears to jump around a few degrees.I dont thing the timing chain is bad the vehicle only has 70,000 miles on it.Do you have any idea how to tell if the vehicle has the booster pump in the gas tank?The factory manual conflicts itself on the location of the cooling fan and fuel pump relays saying they are in the exact same place according to the pictures.When I turn the key on I dont hear a pump running before I start the engine,but I guess it could have died(if it has one)I cant see the wiring to the tank with the exhaust heat sheilds in the way.I hate like hell to have to rip down the exhaust and the heat shields if there is another way to tell.the fuel pump was previously replaced before I bought the car.I wonder if the booster pump may be dead or someone installed a fuel pump that is supposed to work in conjunction with a booster pump and cannot supply the correct pressure when hot.

Vader

You could perform a fuel pump flow test. With a full fuel bowl and separate fuel supply to th ecarb, you can disconnect the inlet line from the carb and divert it to a clean container. The pump should deliver at least a quart of fuel in 30 seconds.

hank

check your sensors map and barometric i had the same problem

butters8435

Volume flow was good when I checked it when the needle broke off in the seat and the vehicle would not start.I overflowed a pint container in about 3 seconds and made a nice mess lol.I know volume is ok I have to figure out a way to rig up a pressure test though.I went to a u-pull-it junk yard today and checked out 6 lg4 305 motors in various vehicles and all of the distributors have around 3/16 of an inch of play in them,so I guess that may be normal for that particular distributor.I checked the map sensor and that was ok.I havent tested the baro sensor yet though.I also pulled the egr valve and it appears to be stuck open slightly.If i spray carb cleaner onto the pintle it leaks into the other passageway.I going to try replacing that and seeing if it solves the problem since it is obviously stuck open and letting exhaust gas into the intake at all times.I'm going to try to find a gm one or a delco one in my area.I'll probably have to order it so it will be a few days till I can post the results.Thanks for all the help guys.Hopefully that will fix it.If not i'll start pullling out what little hair i have left.

Vader

The leak in your EGR is going to introduce a huge vacuum leak.

Didn't I mention a lean/hot condition? Sounds like you may have found the culprit. If you can't find a stock replacement EGR valve, an aftermarket may be O.K. in your case. The CCC system is more tolerant of variation in EGR flow (it's a pretty simply system) and doesn't relay as heavily on a minor changes in the MAP/BARO sensors for finer mixture control.