95 Stops Running When it is Very Hot outside

[dmltml]

Help, My 95 which is very well maintained stops running when the temp outside is above 92 and the car has run for a few hours. The temp gauge was at M. Today I drove for 134 miles at 70 MPH and suddenly it simply stops running. After letting it set for a little while, it started and ran great for about 20 min. Same cycle occurred. When it dies, it just cuts off and growls a little when I give it gas. It will typically start right a way without waiting for 20 min but wont stay running. This happens when the tank is full or nearly empty. It only happens when it is above 92 Degs outside. But after running for 3 hours and it was still 99 deg out, It ran fine (after stopping 4 times). I put a fuel gauge on the car after it failed (about 20 min later) and it was between 30 - 35 Psi. Most things on the car have been recently replaced including the fuel filter.
Thoughts? This happened one other time in the fall driving to atlanta. The only short trip occurrence is after driving for a while on a hot day then making a short stop at the grocery store or ice cream shop and then she struggles to start but will go once she starts. Did a upper and lower 60 about 40,000 miles ago.

 

[SHOdded]

I take it there are no codes? Otherwise, either the CKP sensor is going bad or there's a short somewhere. Check & clean all grounds, check the DIS connectors for cracking, maybe even take off the DIS, clean, fresh grease & re-install. What voltages are you seeing with the engine off/engine running?

 

[RonPorter]

Check your fuel pump pressure, but odds are that your pump is getting weak and you are getting vapor lock. Common problem on old SHOs. It should be 39 psi at the rail, but if you are in the low 30s or lower, that's your issue.

 

[dmltml]

I take it there are no codes? Otherwise, either the CKP sensor is going bad or there's a short somewhere. Check & clean all grounds, check the DIS connectors for cracking, maybe even take off the DIS, clean, fresh grease & re-install. What voltages are you seeing with the engine off/engine running?

I have not pulled codes on the OBD1, I just pulled the camshaft position sensor, There is a bit of oil leaking into the cavity. Probably not good. Seems like the CrankShaft position sensor is a good candidate as well. I replace it about 40,000 miles ago, 3 years ago. not something I can do in the parking lot. I am about 3 hours from home..... Bummer. When you say use fresh grease, I assume you mean on the connectors? I will be cleaning the camshaft sensor area tomorrow and replacing the camshaft sensor since this is cheap and easy.

 

[dmltml]

Check your fuel pump pressure, but odds are that your pump is getting weak and you are getting vapor lock. Common problem on old SHOs. It should be 39 psi at the rail, but if you are in the low 30s or lower, that's your issue.

The gauge I used had a leak so I think I was actually 35-40. What is your thoughts on why this only happens when it is hot. It asks like vapor lock. What is the best way to clear vapor lock?

 

[itwonder]

I recommend using a spark tester, Lisle makes one, to check for spark as you crank it after it cuts off. If spark is good, then that points toward a fuel problem. Once it cuts off, you can try cycling the key from off to on (not start) several times. That will run the fuel pump. Then see if it starts. I'm sorta thinking like Ron, fuel pump if it has not been previously replaced.

 

[rubydist]

ok, you can pull codes and we can help you, or we can just guess - its your choice.

 

[SHOdded]

When you say use fresh grease, I assume you mean on the connectors?

No, I meant the backside of the DIS itself, where it contacts the intake. A thin layer will work fine. I would use computer heatsink grease, but others will say dielectric grease is fine too. Either way.

Should definitely hear the fuel pump prime when you turn the key in the ignition to ON without engine running. How long does the pressure hold after you turn the engine off?

 

[dmltml]

Pulling the following code.
551


Problem in Intake Manifold Runner Control (IMRC) solenoid/circuit – Solenoids
Next steps? Thanks for the help

 

[dmltml]

Fyi. I replaced the fuel filter, it was dirty after only 35k i cleaned and greased the DIS. Replaced the cam sensor. All cheap and easy parts to throw at it. None of these were the issue.

 

[rubydist]

Unfortunately, that was not as helpful as we had hoped. Sometimes codes are not set.

This suggests that your problem is with the crank sensor, because your symptoms are classic crank sensor symptoms and in my experience there is a code only about 50% of the time for the failing crank sensor. The crank sensor is also not particularly expensive, but it is more difficult to change. The most important part is to be sure to set the gap properly - the magnet will want to stick to the shutter wheel, and if you let it do that, it will destroy the new sensor in no time. So, be sure the gap is not too small but also that it is not too large.

 

[SHOdded]

Hope this helps:
http://wikisho.com/wiki/My_SHO_stalls_intermittently;_why?

 

[itwonder]

The DIS should not have grease on it. You need thermal paste on the back of it. The intake is the heat sink for the DIS, and the paste facilitates heat transfer from the DIS to the intake. You can get it at Radio Shack, assuming they still stock it given their business situation, or online. Arctic Silver is a popular brand.

 

[dmltml]

so I did use dielectric grease on the DIS. Yesterday I drive in 97 degree heat for 2 hours and then she died again. Same symptoms Outside temp reads above 97 on my dash, the temp gage is as high as it gets M on the normal readings. she sits for a while, cools down and then will run until we get to M for a while. So yesterday I got far enough north that the temp cooled off, I let her sit in the shade with the hood open and ate dinner. I then proceeded to drive in 85 degree or less temp for 5 hours straight. Here is an interesting clue, I got 28 mpg! I know I was babying her but still. This morning I pulled codes, 172, 176. Lean at the O2 sensors. Does this give more credibility to fuel pump? Also I watched the tac and did not see it drop to zero as she died. Thanks for the help.

 

[SHOdded]

I have squeezed 30 mpg out of the ATX SHO on extended highway runs, rolling hills and all, traffic moving fast. So 28 is not out of reach at all BUT it could definitely be running lean, which makes the engine run hotter. So I would take a closer look at the MAF, clean the sensors and the wiring contacts (use MAF or electrical parts cleaner) thoroughly, look for air leaks after the MAF.

 

[rubydist]

lean on oxy sensors coupled with excellent mileage suggests a vacuum leak in the intake system somewhere. when oxy sensors fail and read lean, typically the engine is running rich and not getting great gas mileage.

in either case, that is not likely the cause of the engine dieing, unless the fuel pump is dieing, in which case you should read low fuel pressure if you test that.

so, the next time it dies, take something and press the schrader valve on the fuel rail. fuel should spray out under 35 psi of pressure. if there is no fuel or just a little dribble, then you will have confirmed that your fuel pump is bad.

 

[dmltml]

Just an update, yesterday I spent a few hours cleaning ground wires and their connections. Most of these connections appear to have been designed for the screw to have the most metal to metal contact. In all cases, these connections were less the ideal and have been cleaned. There are a couple of things of interest I wanted to share. 1. the ICRM module was not being grounded through the case. Not sure if it is supposed to be but the bracket that attaches this module to the body is very rusty. The connections and the screws that connect the bracket and the module were not great either. This bracket was epoxy coated from the factory but appears to have bare metal designed around both of the screws. It is now grounded. 2. The part of the starter relay where the wires connect was a little loose. So as I was chasing ground wires I move the large red wires that connect to the solenoid and the whole black cap would move about an 1/8 of a turn or less. I don't completely understand what happens electronically when the car is started, moving the key from off past ACC to start and back to ACC. I share this (not that fact that I am not a car pro, that should be obvious LOL) but when the car dies, it acts like I accidently turned the key off. It will always fire right back up but is clearly not getting the right air fuel mixture and stalls out. Once it sits long enough for the Temp gage to drop from M to A (normal) it will fire and run well. Next steps, take an Ice pack with me on my drive home Tuesday from Ohio to NC and if she dies, cool down the ICRM and see if this gets me running quicker than previously. If so then I think I know what is overheating. If this fails then I plan on disconnecting the MAS sensor and see what happens. I also plan on ordering a fuel pump and replacing it. What the heck it is 20 years old with 95K on it. Probably the right thing to do anyhow. Rubydist suggested that I have vacuum leak in the intake system somewhere. I can hear a small leak, just need to track it down. It is on the transmission side but cant find it yet. Thanks again.

 

[sperold]

The car will still run with the ICRM totally disconnected from the body.
All of my fuel pumps have over 200K miles and still perform correctly. I have replaced gas tanks and put the original pump back in on a regular basis.
The trick concerning fuel pumps is to never run them low of fuel in the tank. The gas cools the body, and when they become exposed, or near exposed, they run warmer, which is bad for their health.
I would save the fuel pump money and install a new crank position sensor (as suggested by Rubydist) as the no - code situation, on a car that stops, sounds like a crank sensor to me. Heat is the enemy to failing electronics.

 

[rubydist]

I would still suggest checking fuel pressure the next time it dies - that way you can confirm or refute the fuel pump as a problem.

Keep in mind that 20 year old cars typically have more than one problem...

 

[dmltml]

Heading home tomorrow. Wish me luck. I purchased a fuel pressure gauge. Reading 60 with the engine running. Pulled new codes. Now saying 173/177 o2 sensor rich. Before it was lean.

Pulled coded with engine running. 129, 167, 225, 536, 521, 632.