86 cranks but won't turn over
 

I can't get my 1986 to start..it will crank but won't turn over. The car has been sitting for a few years and the previous owner said he had it started it a year ago, but who knows if he was really telling the truth.

There was not much fuel pressure so I replaced the fuel filter, which fixed that problem. I also drained out the old fuel and replaced it with new premium fuel (about a half a tank). Timing and firing order are both fine, and all hoses and wires seemed to be in tact. There was a spark coming from the spark plugs. The car also has a new battery. I also tried spraying starter fluid into the throttle, but the car still didn't start. It seemed like it wanted to start and came real close to turning over but never actually started. One time I sprayed a lot into there and there seemed to be a slight backfire with a small ball of fire. When I started it that time I was opening the throttle while starting it to try and get more air into it.

I'm all out of ideas and was hoping to get a little insight as to what I should try next before I start messing around with everything. The main thing I wasn't sure about was whether or not the problem had to do with the VATS or ECM because I'm not too familiar with them. Oh and the car is an automatic.

good luck. Same problem Im having. You said you replaced the fuel filter and that resolved your fuel pressure. DId you check this with a gauge? Try having someone turn the ignition key and you stand by your gas tank and listen for the fuel pump running

Since you have spark and fuel, I would check the firing order.

I bought an 85 Trans Am that wouldn't run after a tune-up.

Discovered the distributor was 180 degrees off and the previous owner just 'notched' the rotor and turned it around.

I didn't check fuel pressure with a gauge but before changing the fuel filter there was only a dribble of fuel and after it shot out a lot. When the ignition is turned you can hear the fuel filter.

As for the firing order I did checked it and it was correct. I didn't exactly check the timing per say but I rotated the distributor little by little and still nothing. I did mark where it was initially and eventually put it back to that spot.

First, let's straighten this out: Cranking and turning over are the same thing. Cranking but won't start are different.

For a long sitting, not being started engine a basic check of the tune-up is called for. I'd replace the plugs if you haven't already. While #1 is out I'd verify that the distributor rotor is properly positioned in relation to the #1 terminal in the distributor cap.

I'd change the oil and oil filter. While cranking the engine in an effort to start it I'd play close attention to the rise in oil pressure - you wouldn't want to start the engine with no oil pressure showing on the gage.

The backfire you experienced is actually a good sign. Says something's going on but timing setting is not quite right. Timing light time to set it correctly.

I wouldn't go under the valve covers just yet UNLESS there is some indication to do so. Something like the previous owner said he just worked under them doing whatever before he stored the car.

I use to own a 86, did a LOT of mods to the engine so I know my way around it. They're several other members here who know that power plant as well. We'll get you up and running.

Keep us posted.

Jake

My bad that's what I meant..it cranks but won't start. I didn't get a chance to work on it today but I took a video trying to start it yesterday so I'll post it up here. You can hear that it's trying to start but just can't do it.

As for the timing, I'm picking up a timing light from my friend tomorrow so I'll check it then. I'm also going to pick up new plugs and replace them as well so I'll let you know how everything goes.

Here's the video..hopefully it works:


file:///F:/DCIM/100KM341/100_0966.MOV

Engines need hot spark and spark at the right time, fuel and air and in the correct ratio and cylinder compression in order to start and continue to run. Use a timing light while someone cranks to check timing. Bring a grounded wire next to an unplugged spark plug boot while someone cranks, you should see a snappy at least 1/2" spark. A weak spark will not start an engine. Measure the plug wire resistance, they should be about 5000 ohms per foot. Measure the fuel pressure, it should be 35-42 psi and it should hold up for at least 1/2 hour after the ign is off or you may have leaky injector/s or defective check valve in the fuel pressure regulator. Get a noid light at a parts store and check both banks by plugging it into an injector socket while someone cranks. It should pulse during cranking. You can make your own noid light with an LED (light emitting diode) and a series 680 ohm resistor. The homemade light must be connected with the correct polarity. Last, measure compression.

sorry for the long delay but I was out of country for a while..

measured the fuel pressure today and it was 41 psi. When I turned the key it jumped right up for 41, but after a couple seconds it slowly dropped down to around 20 psi and stayed there for at least 10 minutes. When you say the pressure should remain for a half hour did you mean it should remain at 41 or that it should keep some pressure? With the initial 41 psi pressure a good amount of fuel was flowing through, but after 2-3 seconds the flow stopped and the pressure began to drop. If the fuel flow didn't cut off it probably would've produced a half a pint in about 10 seconds.

I'm not sure how to post a video on here but the video I took last time of the engine trying to start I posted on youtube so here it the link:

http://www.youtube.com/watch?v=e-ze6mxcLtQ

Check the plugs, make sure they are gaped properly, and they look clean. Turn off all the lights in the garage, remove the fuse for the under hood lights, and try to crank the engine. Look for any sparks jumping from the wires or cap.

Yes, the fuel pressure should hold steady with the engine having just been turned "off" for at least half an hour without dropping any psi.

I tested mine a few days ago and it held rock steady at 46 psi for over an hour, at which time I terminated the test.

Jake

ECM only runs pump for 2 sec ; key on then stops.
You have to make pump run full time to measure fuel flow ( not pressure )
Regardless of whether system is holding pressure with pump off , rail fuel pressure should return when engine cranking over .
does it ?

Did you follow jfb's advice and check injector pulse with a noid light ?

Get oil into the cylinders either by removing the plugs and putting a squirt in each cylinder. Or thru the intake while cranking. This will restore compression as the cylinder walls and rings are washed dry from all the cranking you have done. You will be amazed at the results.

Let's not get ahead of ourselves. Let's fix the fuel pressure drop first, then move on. Fix 'em as you find 'em.

Jake

Got out the timing light and checked it. Adjusted the timing, to no avail. Pulled and checked the plugs, they looked fine. Nice fat spark, jumped about 1/2 inch like jfb mentioned.

Got a new coil, cap, rotor, and the plugs were changed recently by the previous owner (confirmed by the fact that when i pulled them they looked immaculate).

"Service Engine Soon" is on. Found this site - http://www.corvettebuyers.com/c4vettes/codes.htm - about how to check it. I'm gonna do that as soon as i get a chance but I was kinda curious how much the computer actually has control over and if the problem could be related to that?

Jake - is that with stock equipment?

I took a video of the fuel pressure gauge, http://www.youtube.com/watch?v=ex8QPq_Wxdo

understand what jake is saying totaly about fuel pressure droping and fixing first. One thing you can try if the car is flooding (leaking injestors) is hold the pedal to the floor while cranking this is clear flood mode. Not saying the car is flooded but something to try.

Pull the code and go from there.

Your fuel system has a leak; most likely FPR, Injector, Fuel Pump. Pressure should hold.

Jake

ok, tried pulling code and it just gave me the neutral signal.

The 'service engine soon' light flashed-
12
12
12
then went straight back to
12
12
12

and just kept doing that without ever showing a code between the 12's.
so the code didn't really help.

This is where i'm at now though- My fuel system DOES seem to have a leak as the pressure does not hold. HOWEVER, when i turn the key, the pump does run and there is 42psi to the rail. Now whether or not the fuel is leaking, there should be enough fuel getting to the engine to at least start for a second or two and then sputter out when the fuel pressure starts to drop?

In the video i posted of the fuel pressure gauge, you can see that the pressure doesn't immediately fall off from 40 and the whole time the engine is cranking there is 40+ psi to the rail, and then when the key is turned again at the end pressure snaps right back up. Am I right in thinking that there must be something else besides fuel preventing the engine from starting? There is fuel and spark and air, I don't know what is keeping the engine from starting.

Thanks for your help and i appreciate any future advice :D

it's something other than fuel. If you sprayed starter fluid in it and it didn't start, it's not a fuel issue.

i'm having some pressure problems myself and my car starts and runs down the highway fine.

I watched the video and trust me, I wish my pressure held that good. Ohm your injectors. there's a sticky from Jon addressing fuel injectors up top of this page and there's a video of member Calderone changing out injectors and showing how to ohm the injectors, if you don't already know how to.

Come back and post the results of the ohm and then I think you can move away from fuel.

while your pressure isn't holding beautifully, it's holding plenty to start and drive your car.

If you end up needing injectors, talk to Jon. you'll be able to find his website in the sticky.

Also try the flooded starting procedure. Your injectors could possibly be leaking down.