99 suburban - wont start after rain

[jjkeswick]

'99 K1500, 5.7L, 130K miles, regularly serviced and well maintained, no garage so sits out in weather. About 8 months ago we started to experience no starts after rains, engine would fire off, but not stay running, security light NEVER came on. Took to regular mechanic and had fuel pump replaced (needed it anyway), wiring "repaired" behind dash. No problems till last month, then same started again. Sometimes will start after 5-6 tries, other times will not start till 10-12 hours AFTER rain stops. Security light came on ONCE while driving for 5 minutes, then went out. TSB's indicate possible corrosion in the Passlock sensor voltage, underhood or under body connections, may be reason. Any idea where these are as I would prefer to check them myself to see if simple solution before pay mechanic to find the same. Since did not reoccur for a while after fuel pump replaced, are there connections that would have to be pulled to replace tank that may now be not sealing again with time? Any resource for wiring diagrams for Passlock path?

[BelieveJesus]

Your problem is very interesting! I found your post as I was doing research on getting a fuel pump for 1999 Chevy sub. We have only owned this sub since Nov. 2005, and it cranks but doesn't start. So everyone is suggesting that the fuel pump is what is wrong. However, what caught my attention on your post is the "rain" issue because last night it rained. VERY INTERESTING!! My husband (who has professionally mechaniced in his life) will get a chance to look at it tomorrow or next day; but I am going to show him this posting. Will let you know what he might find out, or at least answer your questions.Thanks/1

[jjkeswick]

UPDATE 7/8/06

Dropped fuel tank and checked connections pins etc, all good, checked voltage to injectors, all good, good pressure at fuel pump and seems to be getting fuel fine as can keep running by providing fuel manually into TBI, checked fuel pump relay, little hinky, left in place started and ran fine yesterday, this AM NO START again, replaced fuel pump relay, still no restart (no rain for 3 days!)

running out of options.... have seen some comments here about ignition switch problem with Passlock switch in ignition switch module............. any other comments on that or other suggestions. I keep comong back to the Passlock sensor OHMS problem from GM Tech bulletin, but cannot seem to find the sensor in any wiring diagrams. Is it in the ECM??

[BelieveJesus]

Originally Posted by jjkeswick

UPDATE 7/8/06

Dropped fuel tank and checked connections pins etc, all good, checked voltage to injectors, all good, good pressure at fuel pump and seems to be getting fuel fine as can keep running by providing fuel manually into TBI, checked fuel pump relay, little hinky, left in place started and ran fine yesterday, this AM NO START again, replaced fuel pump relay, still no restart (no rain for 3 days!)

running out of options.... have seen some comments here about ignition switch problem with Passlock switch in ignition switch module............. any other comments on that or other suggestions. I keep comong back to the Passlock sensor OHMS problem from GM Tech bulletin, but cannot seem to find the sensor in any wiring diagrams. Is it in the ECM??

Hi jjkeswick, when you say you checked fuel pressure, did you use a pressure gauge? what was the pressure at? Chances are you have a plugged fuel filter that sometime just lets enough feul to start and run and sometimes it doesn't. Fuel pressure on a TBI (not vortec) should be 15 PSI. It must be checked with a gauge not just by seeing gas at the injector. When the car is not starting, can you hear the fuel pump run?

[jjkeswick]

Did not check with gauge, don't have one. Went into no start yesterday AM and when I replaced the fuel pump relay with new part, still no start. Called our mechanic to come get it, I'm done. I will ask him to check the fuel filter, but I beleive it was just replaced about 6 months ago, although it only takes 1 batch of bad gas............... thanks for the info.

I will post what the solution was, if ever fixed..................................

[BelieveJesus]

Sorry to hear that it did not start. Did you happen to hear if the fuel pump was running when you tried to start it? Other issues that may come into play would be intermittent short or open wire (very hard to find and diagnose). Another possibility is water in the tank which may be your rain issue. The fuel strainer on the fuel pump in the tank is designed to allow fuel through but not water. So if this is water in the tank is could plug the strainer enough not to allow the fuel through at times but allow enough fuel through to start at other times. Other possible no fuel issues could be PCM (car computer) not priming the relay (what controls the fuel pump relay), bad or loose ground (black wire by tank) at cross member( bolted on cross member) by the front of the tank (could also be affected by rain) are the ones I would look into.

[primal1]

i to am having a similar prob. mine seems to be when it is moist outside. how ever it has never given problems thru deep puddles or thru the car wash with the sprayers spraying into the engine compartment. just this morning was the first time when it died on me while i was driving though. i need help with this one.

[Teamdobbs]

Same type of problem here...Left truck at airport over weekend and it rained all weekend. Took 15 minutes before it finally seemed to get gas and get started (after finally pumping the gas pedal hard). Never had this problem before...now every time we park it, it takes 5 minutes to finally start (good thing it has 2 batteries). I have replaced the Fuel Pump Relay with no change...just changed the fuel filter and will see if it starts later tonight as my wife is now driving it and letting it run when she has to stop somewhere.
--I wouldn't think that it could be the fuel pump as it runs fine once it starts-- Also notice that I can spray in starting fluid and it fires right up but then sputters out like there is no gas. Is there something that could be causing a vacuum and drawing the gas back toward the tank??

[BelieveJesus]

Originally Posted by primal1

i to am having a similar prob. mine seems to be when it is moist outside. how ever it has never given problems thru deep puddles or thru the car wash with the sprayers spraying into the engine compartment. just this morning was the first time when it died on me while i was driving though. i need help with this one.

I will need a little more info. When it died, did the check engine light come on before it died? Are you sure its fuel related or possibly electrical related?When it died did it sputter when coming to a stop or were you going done the road?

[BelieveJesus]

Originally Posted by Teamdobbs

Same type of problem here...Left truck at airport over weekend and it rained all weekend. Took 15 minutes before it finally seemed to get gas and get started (after finally pumping the gas pedal hard). Never had this problem before...now every time we park it, it takes 5 minutes to finally start (good thing it has 2 batteries). I have replaced the Fuel Pump Relay with no change...just changed the fuel filter and will see if it starts later tonight as my wife is now driving it and letting it run when she has to stop somewhere.
--I wouldn't think that it could be the fuel pump as it runs fine once it starts-- Also notice that I can spray in starting fluid and it fires right up but then sputters out like there is no gas. Is there something that could be causing a vacuum and drawing the gas back toward the tank??

Hi Teamdobbs, when you had the fuel filter replaced was it plugged. GM pumps are notorious for burning up on a plugged fuel filter but they don't go out until a few weeks after the filter is replaced. Also just because it gets fuel after trying to start the sub for 5 minutes makes it even more possible for a bad fuel pump. They can be just on the border line of weak fuel pressure where the car will runs sometimes and sometimes it won't. It could also be a bad fuel pressure regulator as well which could cause low pressure. With fuel pumps there are two things to check. Pressure is one but most people don't think about fuel volume. That is a fuel pump can have the correct pressure but not enough volume to have the car run. Just something to look into. I'm not totally convinced that all these problems listed here are due to moisture unless water is intruding into fuel tank or into the fuel system wiring. But I am not ruling it out. When I worked at a Chevy stealership several years ago we had problems with water running into the main firewall wire harness on G vans. It always corroded two connectors that would make the van not crank and it was due to the a new design of the harness that moved it under the water gutter from the windshield. This may be something similar. Ok, I done talking now.

[Teamdobbs]

Fuel Pump was the problem...I broke down and forked out the $$ for fuel pressure test kit and yes that showed that it was the fuel pump...picked up a fuel pump and just finished the install and it now starts and runs great. By the way..yes..it did appear as though the fuel filter was very dirty, when I removed it I had very little gas from the engine side of the filter...as soon as I started connecting the new filter (tank side first) I immediately had gas coming out the engine side.
Thanks for assistance!! God Bless!!

[primal1]

Originally Posted by BelieveJesus

I will need a little more info. When it died, did the check engine light come on before it died? Are you sure its fuel related or possibly electrical related?When it died did it sputter when coming to a stop or were you going done the road?

no the check engine light did not come on. neither did the security light. it does not trigger a service engine soon. the gauges all are in the normal range. it did not run differently before it died. it just seemed like someone reached over and turned off the key whille i was driving.

[BelieveJesus]

Originally Posted by Teamdobbs

Fuel Pump was the problem...I broke down and forked out the $$ for fuel pressure test kit and yes that showed that it was the fuel pump...picked up a fuel pump and just finished the install and it now starts and runs great. By the way..yes..it did appear as though the fuel filter was very dirty, when I removed it I had very little gas from the engine side of the filter...as soon as I started connecting the new filter (tank side first) I immediately had gas coming out the engine side.
Thanks for assistance!! God Bless!!

Your welcome. Remember the fuel injected fuel filters filter down to 10 micons (very small) whereas the old carburetor filters were only 100 micons (much bigger holes). So the fuel injected filters plug up fast. In most cases, normal driving conditions require fuel filter replacement at around 10,000 to 12,000 miles. This will help the pump last longer.

[BelieveJesus]

Originally Posted by primal1

no the check engine light did not come on. neither did the security light. it does not trigger a service engine soon. the gauges all are in the normal range. it did not run differently before it died. it just seemed like someone reached over and turned off the key whille i was driving.

It could be electrical but it is hard to tell without more info. How well do you know cars? Do you have a parts store near you like Autozone that can check for codes for you or do you have a code reader? We need to start somewhere.

[primal1]

Originally Posted by BelieveJesus

It could be electrical but it is hard to tell without more info. How well do you know cars? Do you have a parts store near you like Autozone that can check for codes for you or do you have a code reader? We need to start somewhere.

i've got a cheap code reader from harbour freight, but it's not throwing a code.