PontiacBonnevilleClub.com

I have had my 1995 Bonneville SE for more than a year, and it has been running superbly. It has 143,000 miles, and I put on about 20,000 of that.

A week ago I drove it for about 45 minutes from home, absolutely no problems. I stopped about a half-hour in a store, then on coming out discovered that it would crank heroically, but not start. It sounds like there is some irregular firing, but the engine will not turn over. I had to be towed home.

I should note that this was on a very hot day, about 106 degrees. I noticed that the Bonneville was running warmer than usual, but only about 200 degrees. It normally runs very cold, temperature gauge all the way to the left. I think that the thermostat may be stuck open. But the temperature gauge was nowhere near the red, which is off to the right. The temperature gauge did not even reach straight up. Assuming that the gauge is accurate, there absolutely was no overheating.

We assumed that the Ignition Control Module was faulty, and replaced it. However, this did not change anything. Taking off the engine cover, we noticed an alarming spurt of gasoline from a tiny crack in the fuel feed line. We did a temporary fix for that with a clamp, and it does not leak. I have ordered a Dorman fuel line repair kit, which should give a permanent fix. However, the car still does not start.

Attaching a timing light to each spark plug wire, we can see a good, strong flash on each one, showing that ignition is occurring. That blasted fuel line leak shows that fuel is being pumped up. So what is wrong?

We considered the Crankcase Position Sensor. However, when cranking the engine the tachometer reads a few hundred RPM, which we think shows that the CPS is working correctly, or else the tachometer would not know that the engine was turning. Is there any way to determine for sure if this part is at fault?

We would greatly appreciate any input from the experts here.

Robert

My first thought is that this is a VATS issue. But before jumping to conclusions some testing would be good.
You have pressure at the rail, and spark, I recommend putting a fuel pressure gauge on and verify that fuel pressure is good while cranking. Next step would be to put a 194 light bulb in place of one of the fuel injectors to make sure they are getting signal from the pcm.

Have you tried disconnecting the MAF?

MattStrike wrote:My first thought is that this is a VATS issue...

If it were the typical VATS (security system) issue, would the engine even turn over? It's been a LONG time ago, but as I recall when the VATS acted up on my 93 the engine wouldn't even crank.

95 PCM's aren't exactly iron clad. Try scanning it for codes and see what happens.

Thanks to everyone replying.

I appreciate the suggestion to look at the VATS. I tried a different ignition key, same result. Also the "security" light does not come on during cranking. I believe this eliminates the VATS?

We disconnected the MAF, but it made no difference.

The oil looks normal, as does the radiator coolant.

We plan to connect a fuel pressure gauge (what is the expected reading?), and also check fuel injectors with the 194 light bulb. We're not familiar with using the 194, but we'll figure it out.

The "service engine" light was not on. However, it came on when we disconnected the MAF, and has stayed on. I'm sort of embarrassed to say this, but I don't know how to read the codes in my '95. Apparently I'm supposed to have a device for that? On my '93 I used to read the codes by a blinking light. Can someone point me to a good explanation for how to do it for the '95?

Robert

We pulled out two of the spark plugs, and they look pretty awful. They have heavy carbon deposits all over the tip of the plug.

They are NGK V-Power, which are recommended for the Bonneville, and have run 19,000 miles.

Obviously the first step will be to replace them. Is it a sign that something is wrong to see this? Also, why would this become a "sudden" problem?

I know on my 1993 Bonnie, you can jump diagnostics terminals and count the blinks. I'm pretty sure the 1995 Bonnie is OBD2, though, and I don't know how you would go about doing that for the OBD2 system. See if you can borrow a scan tool, for sure!

One way to tell if you're getting spark (if you've got a steady hand) is to pull the plug, disconnect the corresponding injector and reattach the plug wire to the plug. Have a friend turn the engine over while you hold the threads of the plug against a ground (vehicle frame somewhere). If you do this right, you will be able to physically watch the plug spark without lighting yourself up at the same time... that's not fun at all, lol.

My car did this once and it turned out to be the crank position sensor. But if your timing light is blinking, you should be getting spark... I would take the ICM to a local advance auto and have them test it on a DIS tester if new plugs and wires don't solve the problem. It's possible that you may have gotten a defective one.

Verify that your PCM fuse is good (passenger side fuse panel, I believe) and let me know if any of this produces any different results!

Have you tried clear flood mode? Replace or clean your plugs. Then hold the gas pedal all the way to the floor. Also just because your engine light isnt on now doesnt mean there arent any codes stored in it. Check codes is always the first thing I do. If you cant get your car to a store youll have to buy a scanner the cheap ones can be bought for under 100 bucks.

You need a scan tool to read codes for this car it has 16 pin obd1 connector also check all fuse locations for blown fuses there are several locations for these start at the maxi fuses first then the other two locations inside the as well good luck

Can somebody please name a specific scan tool that works with the 1995 Bonneville? I looked at several, and the salesman said that he did not think they were compatible.

Is there some specific make and model of a scan tool that DOES work with the '95 Bonneville?

IDK unfortunately. I believe the '95 is OBD 1.5 and that ODB II didn't come until 1996. All the scan tools I know (not many) only go back to ODBII. Some claim to go back to OBD 1 and 1.5, but not for me when I tried them. A garage I use to use had one, but he ditched it so he could legitimately say he couldn't scan the Diagnostic Codes. I believe everything is going to CAN(?). Andrew, Lane, or one of the other "gearheads" will know the answer to the scan tool to use question. - BC

Well, the car is running well now, so let me summarize what happened.

The spark plugs were messed up. My friend found a YouTube video in which a mechanic said: to test if you have leaks from anti-freeze onto the plugs, drain the radiator, and let everything dry out. If it then starts up (and only run it a few seconds!), your problem is a leak in the manifold, allowing coolant to get on the spark plugs. "That is ridiculous," I said, but not having any other ideas, we tried that. It started right up!

So, we replaced the upper input manifold, and the gaskets on the lower manifold. This involved removing the fuel injectors, the alternator, and the wires to a bunch of stuff. We managed to do it without disconnecting the cables from the throttle body, which I did not want to disturb. Inside the manifolds, evil orange goo was everywhere, the result of GM Dexcool being used for years. We cleaned everything pretty well, and put it all back together. We replaced the spark plugs with new platinum ones, replaced the O-rings on the fuel injectors, and replaced a few smaller parts while we had access to them. We drained the radiator CONTINUOUSLY (the engine running with the radiator drain open, while being filled at the top) until the color of the water coming out was no longer ORANGE, but clear. This took longer than you might think. We then filled the radiator with water and normal green anti-freeze.

About the only issue remaining is that when the car first starts after completely cooling off, the idle runs too fast (around 1500 RPM), resulting in a big "clunk" when you shift into gear. After running for a few minutes, it reverts to the normal idle speed of about 1000 RPM. We replaced the Idle Air Control Valve, the old one was dirty, but this made no difference.

As for the device to read the codes, I understand that these are supposed to work: http://www.ebay.com/sch/i.html?_sacat=0 ... ron+cp9145. Somebody please correct me if this is wrong. At present, my "check engine" light is not on (no major code present).