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I've got an 86.5 928S, I've recently got it running for the first time (had to take it to a shop) and picked the car up over the weekend. I trailered the car home (4 hours) and unloaded it. Somewhat excited to drive the car for the first time I started the car and let it warm up. It ran great and idled for around 10 minutes. I'm close to a gas station and I knew there wasn't a lot of fuel so I drove the car about 5 blocks and filled up the car. Started the car to leave and I noticed it stumbled and died. Restarted the car and it came around and idled again. I pulled out of the station and started to go through the gears, not running hard but just normal driving. I had just shifted into 3rd gear and started to accelerate when the car died and I coasted to a stop. No start. I walked home to get a truck and trailer and returned to pick the car up about 30 minutes later. Just for fun I gave it a try and it started, I immediately headed back to the house and where the car again died but close enough where I coasted to the curb out front and parked it. I tried about three hours later and no start at all. We pushed the car back inside.
The following day I thought perhaps it could be a fuel filter although it was just changed so kind of desperate I switched out to a new spare filter I had. The car actually started and I thought, briefly, I had figured it out but within two or three minutes of idling the car started to run erratically and finally died. tried to restart and was able to but only runs for a second or two and dies.
I'm way over my head on this car. I'm not a mechanic and had no business buying one of these but always wanted one so I did. The car came to me as a non running car which had sat for a period of time. I've since spent over $20k on it (another $5700 last week) trying to get it running. Everything I can think of has been replaced from the heads up. All new fuel lines, vacuum lines, full top end, pressure regulator, injectors, fuel pump, fuel filter. There is countless other stuff but the only thing I can think of is the fuel pump relay. Can that fail intermittently? I imagined either that would work or not but definitely don't know for sure. Do fuel pumps fail within the first 30 minutes? Is that possible? It's from 928SRUS, not Ebay. I wish I could take it back to the mechanics but that costs a fortune and is 4 hours one way away from me. It's winter here in Minnesota so I guess it's not a big rush but the money is definitely a concern. I'm going to be $25k in an $8k car soon. My wife absolutely despises the car and thinks I should just junk it and cut the losses. I'm sad to say I really have come to dislike it myself and the fun of owning it has long been replaced by stress and regret but what do you do at this point?
Thank you for the links! It will be next weekend before I can have another go but I'll check that out. Probably just order a relay in the meanwhile and replace.
Also look at all your grounding points, get to them(some are hard to reach) and clean each one with some fine sandpaper. Also the negative ground strap should be looked at. Buy a relay puller plyers and get some contact cleaner, pull every one and clean them. Do all this while checking the fuses, and cleaning them.
Easy way to eliminate the Fuel Pump Relay as a possible culprit is to jumper terminals 30 & 87 which will make the pump run continuously. If the car starts and keeps running, you know it's the relay.
I had an issue recently where the car would be driving along fine and then feel like it was going to die, then run totally fine again. One day, just out of the blue it completely died - coasted to a parking lot and started doing some diagnostics - swapped FPR with horn relay - no dice, watched the tach when I tried to start it and no movement. Removed airbox to find my connector for the crankshaft position sensor had come completely apart even though both plugs are in good shape. Put it back together and fired right up. Wire tied the connector together when I got home.
Do you have tach needle movement when the starter is cranking? If not, start with the CPS and wiring.
All great ideas guys and I appreciate the help and these are things I can do without spending much money.
I have another question, when I changed the fuel filter last night I had anticipated a steady flow of fuel through the pump from the tank but instead there was only about a cup. Shouldn't fuel from the completely full tank have gravity fed through the pump or is there something in the pump blocking it? Could there be a pre-filter in the tank that is plugged from when it sat with old fuel?
Yes the tank strainer could be clogged the fun part is draining out 20 gallons.
UMM I would have thought that any shop doing the work you described would have put 50 to 100 miles on the car prior to releasing it,
so to root out any bugs.
That said Dont get discouraged it sounds like your on the right path,
and it could also possibly be an electrical issue like a bad relay
OOPs post 7 already suggested this
You should replace the 4 running relays
the X bus relay
the fuel pump relay,
the LH relay ,
and the EZK relay
NOTE do one at a time then try to start the engine.
NOTE if you smell gas from the exhaust then hold the pedal to the floor while you crank it, as you could have a bad damper or Fuel Pressure regulator
Please post some pictures of the car and the engine bay
Yes the tank strainer could be clogged the fun part is draining out 20 gallons.
UMM I would have thought that any shop doing the work you described would have put 50 to 100 miles on the car prior to releasing it,
so to root out any bugs.
That said Dont get discouraged it sounds like your on the right path,
and it could also possibly be an electrical issue like a bad relay
OOPs post 7 already suggested this
You should replace the 4 running relays
the X bus relay
the fuel pump relay,
the LH relay ,
and the EZK relay
NOTE do one at a time then try to start the engine.
NOTE if you smell gas from the exhaust then hold the pedal to the floor while you crank it, as you could have a bad damper or Fuel Pressure regulator
Please post some pictures of the car and the engine bay
Roger is sending all the relays to swap out the aforementioned relays along with a cam position sensor connector. Thanks to all the help here and from speaking to Roger I have a list of things to check. The fuel pressure regulator was just replaced at the shop. I can't say for sure on the dampers but have to believe they would have checked this. Maybe not though. I requested they drive the car but the tires are quite old and weather checked pretty bad and they said a test drive wasn't possible, The tires are pretty bad but I feel they could have gone a mile on surface streets at 30 mph but can't really fault them for that I guess.
I guess I just had to vent to someone as the frustration level with this car is currently pretty high. It must be some kind of fairly simple issue at this point and with a little diagnosing probably will be sorted out. It's been 3 years since purchasing the car and I was pretty excited to finally drive it. lol
Some of you may remember this car from the original post:
From the point the original thread ended this car went to a shop in Chicago called My Nine Eleven Shop which ended up in a total disaster. They tore the car down as it ended up needing intake valves on a couple cylinders due to timing belt jumping. After disassembling everything the first week the car sat untouched. The 4 - 6 weeks estimate had passed by and soon weeks of waiting turned to months. By January (13 months later) I gave up and picked my car up as a rolling chassis with the engine torn down and 5 large cardboard boxes full of parts from everywhere. Stuff just thrown together without a care in the world. Believe it or not I had to pay this clown $2600 to get my car back as a pile of parts. I won't mention the name but a very helpful Rennlister whom had walked me through stuff on the phone told me to bring the car to his shop and for a very meager amount he would try to reassemble the car. (basically felt really bad for my situation) The only thing the first guy did successfully was to get the heads reconditioned by an outsourced (thank God) machine shop. The gentleman that took on the task soon realized what a mess he had on his hands and how many things were missing. This resulted in over $14k in parts orders from Roger and a few from Gregg. All new wiring harnesses from Sean (I believe) An improved engine dampner from Gregg (nearly a grand), Porken tensioner upgrade, new twin disc clutch. Upgraded fuel lines, new MAF and all rubber parts. New power steering rack and it just goes on and on. I was able to pay three times what was asked for in labor but honestly it likely wasn't enough for all the time he had sorting out the mess. In the end he had to send it home with me as his business needed the space in the shop and I didn't want it to be any more trouble so I picked the car up not running but almost. (Ran rough still) The car sat for this last summer until I took it to a shop in the Twin Cities. They sorted out a few more issues and we ended up with another $5700 bill. (Porsche shops aren't cheap!) and that brings us up to current. So when I say i'm over $20k in, I really am. Hope this helps understand the frustration of hauling it home as a non running car for the fourth time.
Roger is sending all the relays to swap out the aforementioned relays along with a cam position sensor connector. Thanks to all the help here and from speaking to Roger I have a list of things to check. The fuel pressure regulator was just replaced at the shop. I can't say for sure on the dampers but have to believe they would have checked this. Maybe not though. I requested they drive the car but the tires are quite old and weather checked pretty bad and they said a test drive wasn't possible, The tires are pretty bad but I feel they could have gone a mile on surface streets at 30 mph but can't really fault them for that I guess.
I guess I just had to vent to someone as the frustration level with this car is currently pretty high. It must be some kind of fairly simple issue at this point and with a little diagnosing probably will be sorted out. It's been 3 years since purchasing the car and I was pretty excited to finally drive it. lol
Some of you may remember this car from the original post:
From the point the original thread ended this car went to a shop in Chicago called My Nine Eleven Shop which ended up in a total disaster. They tore the car down as it ended up needing intake valves on a couple cylinders due to timing belt jumping. After disassembling everything the first week the car sat untouched. The 4 - 6 weeks estimate had passed by and soon weeks of waiting turned to months. By January (13 months later) I gave up and picked my car up as a rolling chassis with the engine torn down and 5 large cardboard boxes full of parts from everywhere. Stuff just thrown together without a care in the world. Believe it or not I had to pay this clown $2600 to get my car back as a pile of parts. I won't mention the name but a very helpful Rennlister whom had walked me through stuff on the phone told me to bring the car to his shop and for a very meager amount he would try to reassemble the car. (basically felt really bad for my situation) The only thing the first guy did successfully was to get the heads reconditioned by an outsourced (thank God) machine shop. The gentleman that took on the task soon realized what a mess he had on his hands and how many things were missing. This resulted in over $14k in parts orders from Roger and a few from Gregg. All new wiring harnesses from Sean (I believe) An improved engine dampner from Gregg (nearly a grand), Porken tensioner upgrade, new twin disc clutch. Upgraded fuel lines, new MAF and all rubber parts. New power steering rack and it just goes on and on. I was able to pay three times what was asked for in labor but honestly it likely wasn't enough for all the time he had sorting out the mess. In the end he had to send it home with me as his business needed the space in the shop and I didn't want it to be any more trouble so I picked the car up not running but almost. (Ran rough still) The car sat for this last summer until I took it to a shop in the Twin Cities. They sorted out a few more issues and we ended up with another $5700 bill. (Porsche shops aren't cheap!) and that brings us up to current. So when I say i'm over $20k in, I really am. Hope this helps understand the frustration of hauling it home as a non running car for the fourth time.
What a horror story. If the new parts don't fix it, I'd recommend you tow it over to the Buckeye Landsharks in OH. Those guys (Joel, Mike, Brad, etc) take on work on other peoples cars and are very knowledgeable about all things 928 and would be able to get it sorted out and running for you.
All great ideas guys and I appreciate the help and these are things I can do without spending much money.
I have another question, when I changed the fuel filter last night I had anticipated a steady flow of fuel through the pump from the tank but instead there was only about a cup. Shouldn't fuel from the completely full tank have gravity fed through the pump or is there something in the pump blocking it? Could there be a pre-filter in the tank that is plugged from when it sat with old fuel?
The tank strainer has been suggested a couple of times, starting with your original thread. You asked about a fuel tank in one thread, but I don't see any mention of the strainer being checked.
There is indeed a strainer in the tank, part of the tank fitting that feeds the fuel pump. It is a very fine mesh, not really a filter. Its purpose is to stop the crap that might jam the pump. (Small stuff gets filtered out by the external fuel filter). So certainly it could be clogged-- especially since the car has sat for long periods. And the tank may have a lot of crap floating around.
So the greater concern is that the strainer has deteriorated, allowing larger chunks to get through and jam the pump. The result is no fuel pressure, which also matches a symptom that you reported early-on: No-start, new-looking fuel pump replaced and the engine ran (albeit badly). That's classic jammed pump.
You can get a look at the tank and strainer by pulling the fuel-gauge sender, under the carpet in the rear on the right side. NOTE that the level needs to be down a bit (maybe 3/4 full, max) or fuel will spill when the sender is loosened. If the tank is full, drain 5 gallons or so-- pull the hose from tank to pump and drain it into a jug. Small vice-grip pliers are great for clamping off the hose. And get a spare hose.
Alternately, disconnect the filter (which you've done already), attach a hose and jug, and power the pump-- jump it at the relay socket (described previously). I cannot recommend jumping the pump directly at the pump connections, sparks and gasoline are a very bad combination.
Then disconnect the cable and return-hose from the top of the tank at the sender, remove the big plastic nut, and pull the sender. And peer inside, you will see the strainer and any junk floating around. And order a new seal and plastic nut, cheap insurance against leaks.
And generally, when Stan (MrMerlin) suggests something, it is a very good idea to take it as gospel. It is easy to approach a checklist as "check this or that or the other thing", but that's not what is meant: Check this AND that AND the other thing. I don't mean this unkindly at all, but these cars were the most complex design that Porsche had done at the time, and now they are old and complex. You've got to be absolutely methodical, ask questions when unsure (long before you get terminally frustrated), follow up with what you found, and most of all be careful.
Last edited by jcorenman; 11-28-2023 at 09:43 PM.
Reason: speling
The tank strainer has been suggested a couple of times, starting with your original thread. You asked about a fuel tank in one thread, but I don't see any mention of the strainer being checked.
There is indeed a strainer in the tank, part of the tank fitting that feeds the fuel pump. It is a very fine mesh, not really a filter. Its purpose is to stop the crap that might jam the pump. (Small stuff gets filtered out by the external fuel filter). So certainly it could be clogged-- especially since the car has sat for long periods. And the tank may have a lot of crap floating around.
So the greater concern is that the strainer has deteriorated, allowing larger chunks to get through and jam the pump. The result is no fuel pressure, which also matches a symptom that you reported early-on: No-start, new-looking fuel pump replaced and the engine ran (albeit badly). That's classic jammed pump.
You can get a look at the tank and strainer by pulling the fuel-gauge sender, under the carpet in the rear on the right side. NOTE that the level needs to be down a bit (maybe 3/4 full, max) or fuel will spill when the sender is loosened. If the tank is full, drain 5 gallons or so-- pull the hose from tank to pump and drain it into a jug. Small vice-grip pliers are great for clamping off the hose. And get a spare hose.
Alternately, disconnect the filter (which you've done already), attach a hose and jug, and power the pump-- jump it at the relay socket (described previously). I cannot recommend jumping the pump directly at the pump connections, sparks and gasoline are a very bad combination.
Then disconnect the cable and return-hose from the top of the tank at the sender, remove the big plastic nut, and pull the sender. And peer inside, you will see the strainer and any junk floating around. And order a new seal and plastic nut, cheap insurance against leaks.
And generally, when Stan (MrMerlin) suggests something, it is a very good idea to take it as gospel. It is easy to approach a checklist as "check this or that or the other thing", but that's not what is meant: Check this AND that AND the other thing. I don't mean this unkindly at all, but these cars were the most complex design that Porsche had done at the time, and now they are old and complex. You've got to be absolutely methodical, ask questions when unsure (long before you get terminally frustrated), follow up with what you found, and most of all be careful.
I appreciate all this good info. I didn't know how to get access to the tank before so that is good to know. Question for you or others, this fuel pump (less than 30 minutes run time and less than 3 months old) is plugged from debris, is there any way to clean it? Sucks to toss it in the trash as they're $200 each.
Last edited by gandalfthegray.; 11-29-2023 at 10:52 PM.
11-27-2023, 12:19 AM
Running out of fuel
