Possible failing fuel pump. - 986 Forum - The Community for Porsche Boxster & Cayman Owners

papasmurf · 11-04-2024, 07:06 AM

About 2 weeks ago I backed the car out of the garage to wash it and an hour or so later was going to put it back in the garage but the car would not fire but just crank over. I tried about 3 times to get it to start back to back with no luck and then waited about 5 minutes before trying again where it fired instantly and ran as normal. I drove the car the next day without issue and parked it until this past week when again it would not start after two extended tries. I went about my day and tried it again that same evening and it started as normal. The first time I just chalked it up to being a fluke and thought maybe something got wet but I have washed the car hundreds of times the same way without issue. Yesterday I started the car to get some gas and it seemed to do the same thing again before again running as normal. When I tried to fill up the car within 2-3 seconds of trying to fill the tank it came gushing out like a geyser covering me and the front of the car. I tried it a second time and it did it again though it might have been possible to slowly fill the tank but I did not try as something was certainly wrong. I have spent time searching here and through google on general and some of the possible no start issues would be a fuel pump that may be dying, fuel pump relay, or Crank position sensor. The problem I have had so far is the problem seems to fix itself before I have time to diagnose the issue with a fuel pressure gauge, etc. Does a failing fuel pump just suddenly die or is it possibly a progressive thing? Could the issue with the fuel filler be related? The timing seems very coincidental?

Deserion · 11-04-2024, 09:24 AM

What year is your car? Does the tach move when cranking?

papasmurf · 11-04-2024, 11:33 AM

2000 model... I have not had the foresight to look at the tach when it has happened to rule out the CPS until just recently.

elgyqc · 11-04-2024, 12:45 PM

I had a bad CPS. The car started when cold. When warmed up it would not start, but if left for about an hour it would start and run until the next time it was turned off.

papasmurf · 11-04-2024, 07:44 PM

I forgot to mention that I do have a durametric but not sure that I could easily find the problem with it either.

78F350 · 11-04-2024, 08:16 PM

Due to the fueling issue, I'd look at the threads that come up in this search:
https://duckduckgo.com/?q=site%3A986forum.com+regeneration+valve+&t=fpas&ia=web

"Regeneration Valve"

Or another part of the evap system.

papasmurf · 11-14-2024, 01:57 PM

breather valve assembly unbolted as I was not getting the "click" that people described you should be getting with a functional unit. I was shopping around to purchase the valve and hopefully fix the problem when I noticed these wires that were damaged. Is the narrow cylinder the magnet that people have described that is part of the valve? I can't see exactly where it goes and I was very slow and methodical when taking the assembly off to hopefully not damage or lose it like people reported. The other wire is obviously broken in half and I suspect this is rodent damage based on some droppings I have seen in the garage lately. I do not see exactly where the other broken end is though?

papasmurf · 11-21-2024, 05:44 PM

to replace the sensor/wiring that was chewed through. I checked the fuel filler after putting everything back together and I now get the "click" when the fuel filler valve is opened that was missing before. The car was very low on gas before and was now showing about 1/4 tank and the fuel light was no longer illuminated as I headed to the gas station to fill it up. Unfortunately I immediately was doused with gas again as it evidently did not solve the problem so back to the drawing board with I guess replacing the fuel valve assembly. I put about 6 gallons in the tank slowly and carefully and drove the car about 15 minutes to my parents house. The car sat for about 30 minutes but would not restart again and is "dry" cranking like it had done before. I let the car sit again for about 2 hours and still could not get it to start. I am going to go back over there tomorrow and see if the durametric will show anything. The CEL l had before is now gone due to the car being unplugged while I was waiting on parts to arrive.

78F350 · 11-21-2024, 06:41 PM

In my previous post I didn't have time to track down the exact thread I was trying to remember. Here it is: Success! Finally fixed the hard start while hot and fueling issues.
San Rensho has a pretty good discussion. Note the posts that mention pinching off a hose as a method of troubleshooting.

papasmurf · 11-22-2024, 11:18 AM

clamping off the vac line from the TB the car started pretty quickly after a couple of prior tries without the line clamped. I removed the clamp and the car idle as usual. I turned off the car and it would not restart with the line unclamped...clamped it again and it started so at least part of my problem is solved. I am not 100% certain it is related to the fueling overflow issue but it may be. I found evidence that my rodent issue had found it's way to the engine compartment but I haven't seen any damage there as well as the rear trunk and headlight areas on each side. He did disable my front turn signals by chewing into the harness. The car is driven about once a week to every two weeks at least so I am somewhat surprised about the rodent issue and I have spent some time working on it during the summer fixing stripped convertible top transmission gears so it is not like I haven't been in or around the car but it seems like it is a pretty recent problem.

Gilles · 11-22-2024, 01:40 PM

Quote:

Originally Posted by papasmurf

The car is driven about once a week to every two weeks at least so I am somewhat surprised about the rodent issue and I have spent some time working on it during the summer fixing stripped convertible top transmission gears so it is not like I haven't been in or around the car but it seems like it is a pretty recent problem.

Papasmurf, it seems that the solution for your problems could be a Texas size kitty cat..?

papasmurf · 11-22-2024, 06:53 PM

on. I tried the start the car about an hour later after having success without the clamp on the vac line and it ran for about 1 second before dying. I put the clamp back in place and could not get it to start again after many repeated tries. I went to the auto parts store to rent a fuel pressure tester and there was no pressure on the fuel rail. I checked the fuel pump relay and tried jumpering the relay as well but again no luck. I pulled the battery tray and checked the voltage on the big 4 wire plug (fuel pump I am assuming) on the fuel tank and got 12V on one wire and a little less than 5V on another so it seems the relay is working correctly as I measured it the same with the relay and with just the jumper wire. The fuse for C4 was fine as well. As the daylight was dwindling I hooked up the durametric and ran through the system tests. The car failed the secondary air system readiness test as well as the fuel tank ventilation test. I cycled through some of the related activations and the charcoal filter shut off valve I could hear cycling but the fuel evaporative valve activation did not seem to work (send command failed). Does anyone know what the smaller plug on top of the fuel tank is for...it is three wires...these were nibbled on as well but were still intact.

papasmurf · 11-30-2024, 11:59 AM

update: I got the new pump in yesterday and the car started immediately without issue...drove it about 20-30 minutes and then again an hour or two later without issue. I was able to fill the gas tank using some gas from a gas can without issue though I doubt the output was as much as gas pump. I drove the car again today for about 2 hours without issue and filled the tank up at the pump without issue but admittedly I was pumping gas at about 2/3 the normal rate as I wanted to be careful and not get doused in gas again. The spoiler issue seems to have fixed itself as well so maybe it had just been a while since it had been cycled up/down. I bought a no-name pump like many have and read plenty of reviews of them being wired backwards but the pump I got was wired the same as the factory unit and went in without issue.

Starter986 · 12-01-2024, 03:42 AM

Quote:

Originally Posted by papasmurf

update: I got the new pump in yesterday and the car started immediately without issue...drove it about 20-30 minutes and then again an hour or two later without issue. I was able to fill the gas tank using some gas from a gas can without issue though I doubt the output was as much as gas pump. I drove the car again today for about 2 hours without issue and filled the tank up at the pump without issue but admittedly I was pumping gas at about 2/3 the normal rate as I wanted to be careful and not get doused in gas again. The spoiler issue seems to have fixed itself as well so maybe it had just been a while since it had been cycled up/down. I bought a no-name pump like many have and read plenty of reviews of them being wired backwards but the pump I got was wired the same as the factory unit and went in without issue.

Happy to hear you got it sorted out!