Good evening,

Have an '87 Trans Am, LG4, and starting the car cold after sitting overnight has become a problem

I rebuilt the E4ME Qjet, as per the stickies here on TGO, including the JB-Welding of the bowl undersides, last April. The choke mechanism, vacuum pulloff, TPS, and the MCS are verified functional and properly adjusted

The car started perfectly during the spring and summer, with the choke snapping shut before cranking, and opening slowly during warmup, as is the case even now. Now that I see morning temps in the 20's/30's, the car won't start dead cold unless I use starting fluid down the primaries. It'll start, then occasionally run and shake violently for about 10 secs., then smooth out like normal. Going without saaying, the use of starting fluid shouldn't be necessary every time I want to start the car dead cold from sitting overnight. I have verified that the accelerator pump shoots gas down the bore, but the choke plate is wet with gas after an extended starting session...that is without pumping the gas pedal, and before using the starting fluid. A 3-4 sec. squirt down the barrel, and it starts.
Help please

 

Other details that I think are relevant are:
1) The mechanical fuel pump, I suspect, is on its way out, as it's operation is so noisy that I initially thought that a lifter had collapsed.
2) MPG seems to be strangely variable. For my 53 mile daily commute, mostly highway, I use 2 1/4 gallons of gas on a good day, and almost a full gallon more on others. My driving habits are consistant, with the lead foot abated for the sake of MPG. EGR Function, vacuum leak, EST problem? The ECM throws no codes.

 

If adding starting fluid cures what ails it, then it doesn't have enough fuel, otherwise. Pretty simple stuff right there. (see my signature for logical help)

Since it doesn't really get very cold in Michigan, being on the "warm" side of Lake Michigan, and since that's where GM is headquartered in the first place , the car should feel right at home.

Here's the "official" starting instructions from the 83 OM, which will apply to your 87 just as well, since it's basically identical in every way. Note however that with modern fuel, it tends to take a couple more pats of the pedal to pump enough of that watered-down cat pee into there to where it actually accidentally becomes flammable, compared to the dog pee they still had access to back in the 80s. So where it says 1 or 2 presses of the pedal, might want to make it 4 or 5.

 

Thanks Sofa, I'll try exactly that, first thing tomorrow, and report back with the details :-)

 

Sorry for the long response time, as I've been caught up with work and lower back pain .

Anyway, pumping the pedal more only made it behave like it was flooded. Using the starting fluid got it running, as usual, but violently for the first 15 secs., feeling and sounding like a giant Harley V-twin. It immediately smoothes out to a normal warmup after the convulsions.
I dunno...maybe the spark is weak or something on cold startup? I'l nose around as much as needed to find the gremlin

 

Same situation this morning...

 

Bumpety bump...

 

Assuming the choke plate is closing fully and it won't start (except on starting fluid) I'd start suspecting a weak spark. Your 87 should have a separate coil. Pop it off and crank with a nail or something stuck in the end of the coil wire and held near a good ground location. Don't get "bit" by the spark, please. Be careful.

There should be a nice hot, blue spark. If it's yellowish-looking, it's weak. Which would be a "report back" situatation.

 

Yes, It indeed is equipped with the stock small cap HEI/divorced coil setup.

I will definitely have to perform the spark check. That choke plate snaps shut tightly every cold start, and the vacuum pulloff opens it up once the engine develops vacuum, hence my confusion. Perfect starting when warmer out, pure poo now...

Will report back with details once found...

 

What part of Michigan are you in?

 

Sorry for the delay, I've been distracted with work and more

I'm in Ypsi, at EMU. I commute to one of my jobs in Livonia.

 

Too bad your so far away. I have plenty of spare parts I would be willing to part with that would probably get you going. Sounds to me like a weak spark as well. Have you tried checking the coil as Damon suggested. You may also want to pull the plugs and inspect them. Kinda sounds to me like what I noticed when I used the stock spark plugs after I swapped Vortec heads into the car.

 

Hey there been reading your post and I have an 84 LG4. Was wondering if you considered a carb rebuild. Before mine was rebuilt it was alway a bit quirky in the mornings doing things like taking forever to start and loading up or running lean until one day it wouldnt start at all. Come to find out it was trash in the carb. It was the original carb for my car and had never been rebuilt. The car runs great now so it might be worth considering.

 

have you run a compression check on it- you need cylinder pressure to allow things to fire easily when it's cold outside..
if the car has a lot of miles on it- like over about 50,000- and it's still got the stock timing chain, i'd bet that your cam timing is retarded, which bleeds off cylinder pressure, which makes it harder to start. this also drags your ignition timing back, too.
also, the cam is probably going flat, which also contributed to lower cylinder pressure- it's normal, all small blocks do it eventually..
it's easy to check the timing chain- line up the timing mark on the balancer to TDC. pull the distributor cap off, and see how far you can turn the crank before the rotor turns. more than a few degrees and the timing chain is worn. more likely, the nylon gear on the cam is worn.

the good news is that you can get all the parts- cam, lifters, timing chain, gaskets, etc.- for about $120 or so if you don't need to have name brand parts and can settle for a Speed Pro cam instead of something in a box with a Comp, Crane, or Edelbrock logo on it..

 

Sorry for not responding to the latest posts on this thread. I've been dealing with complications from a prior back injury, so I've had little under-the-hood time. I'll be poking around soon enough, as soon as this schizo Michigan weather takes it's pain pills...at the same time as I do