1990 Bonneville Curious Starting Issue

Hello all! I'm new to the forum due to a curious starting problem with my 90 Bonneville. The problem is that it will not start after it has been rained on. It will turnover but not fire. It will, however, start with a shot of ether into the throttle body. This is a cold start only. It will start just fine after it is warm. Before I narrowed it down to only after it had been rained on, I replaced the ignition module, coil and fuel pump (in addition to the fuel lines as they were rusted) as my first guesses. The spark plugs and wires are also just fine. The harmonic balancer has also been replace due to different issue with it. Could it be related to something getting moisture near that area? My first thought was electrical but the ether solution leads me to believe it is not.

That is strange.....try starting with the MAF disconnected.......also check the fuel pump regulator vac line....see if it has fuel in it....

This is classic boarderline fuel pressure problem for the 4.3 poppet valve system......your vehicle is nothing like that....but you say it runs fine once it starts, and only happens when it rains?

That is strange.....try starting with the MAF disconnected.......also check the fuel pump regulator vac line....see if it has fuel in it....

This is classic boarderline fuel pressure problem for the 4.3 poppet valve system......your vehicle is nothing like that....but you say it runs fine once it starts, and only happens when it rains?

Yeah it's really curious that it is only after it had been rained on. It had done it periodically at anytime then got worse and worse. Then I replaced the fuel pump and now it only happens when it rains. My latest thought is that it might be Air Charge Temperature sensor as the check engine light came on and (I think) that is what it read.

check ur crank position sensor cover, it could be letting water in and screwing with ur sensor its right behind the harmonic balancer(or it should be)

Thanks for all your help and ideas guys. I had another project I wanted to do, which was replace the valve cover gaskets, intake manifold gaskets, spark plug wires(worked fine but old) and discovered that my oxygen sensor was actually broken in half and just sitting there. So, after replacing that and a thorough cleaning, it is starting and running like new again.

So, after replacing that and a thorough cleaning, it is starting and running like new again.

Little confused here.......O2 sensor has nothing to do with startup of the vehicle......what do you mean by a thorough cleaning?

With the O2 sensor broken, should have been a code 13 set in the ECM....

If you changed the spark plug wires, that was probably the reason for your hard start when it rained....

So, after replacing that and a thorough cleaning, it is starting and running like new again.

Little confused here.......O2 sensor has nothing to do with startup of the vehicle......what do you mean by a thorough cleaning?

With the O2 sensor broken, should have been a code 13 set in the ECM....

If you changed the spark plug wires, that was probably the reason for your hard start when it rained....

After my original post, it began it's fickle starting in the garage as well after it was dry. It wouldn't start cold, although rain had effected it as well. I never got a code 13. I got codes 21 and 34 which prompted me to clean my throttle body and MAF sensor, in addition to the intake manifold. Lastly, I re-o-ringed the fuel injectors as those had seen much better days. I'm guessing it was dirty air passages that led to its erratic starting frequency. I thought I had it nailed down with the moisture but that wasn't it exactly it. I decided to go forward with the valve cover and intake manifold gasket set project and hoped I figured it out there.

Maf failures common in those years, as well as the harness
/plug to the sensor.

Change keys!

What does the key have to do with it? The key has a resistor pellet on it, but if that was the problem, the vehicle wouldn't crank.....it cranks, but doesn't fire....

Wow... The key has nothing to do with the starting of this car... The 90-91 Bonnevilles do not use the Passkey system... So thats out the window...

Fuel pressure should be 38-41 Psi, need to verify the fuel pressure first, these cars as they aged did have issues with leak down of the fuel pressure regulator... This could cause a hard cold start as the pressure would be dead low... On the next cold start cycle the ignition on and off a few times and then start... see if this changes anything..

If that does nothing, then on the next cold start crack the throttle open a tad, just needs to be very little... If it starts right away then the IAC passage may be gummed up and require cleaning...

Also we have had people that have had issues with the Magnavox style Ignition Control Module that would cause a hard start with moisture and or cooler temps... So that would be another possibility...


But first things first, Rule out the fuel pressure...

Hey guys. I just went through the same thing. to think every one is right about the grounds. I fixed mine by pulling the kick panels both left and right, pulled apart the buss connector ,cleaned and soldered all spades .these are the main grounds . also on the pass side is the grounds for the fuel pump(SOLDER,SOLDER,SOLDER)these. for they will keep the pump relay from turning on for fuel pump. water from windshield can drip down into this relay and fuse and corrode( passenger side kick panel for relay and pull carpet over to expose wire harness and untape the plastic connector and remove cover or just cut all the wires and solder them togather . also there is a ground buss in the trunk, do the same as above .Same goes for trucks and Suv. Water is the main prob ,windshield seals are no good as it gets hard over time and pulls away causing the leaks. even though these connectors may look okay but they can become lose over time by just shutting the door. It's worth the time to remove the plastic cover to expose the spades and jumper bar and clean and SOLDER. you might be surprised how many things you'll fix just buy doing this.