'86 928S cranks but engine won't fire up
03-03-2015, 06:11 PM
#1
Track Day
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'86 928S cranks but engine won't fire up
Hello all...I'm new to 928 ownership (3 weeks)...hopefully some of you veteran 928 owners can help out. Have owned 944's, but the 928 is a different beast altogether...
The vehicle has been running seemingly fine since purchased, other than the fact that I've noticed it takes about three seconds of cranking before the engine fires up. It will stumble, but I can usually feather the throttle pedal to coax it along. Otherwise it will stall, and I'll have to re-crank once.
Ironically, I never hear a fuel pump kick in in the ignition start position like other cars -- is this normal?
Two days ago, I backed it out and gave it an exterior wash (again), cranked it back up and parked it without drama. Last night, I went to move it again and it would just crank but that's all. It's almost as if it's not getting any fuel delivery.
Today, I checked all the related relays and fuse in the panel, and they all look fine. The previous owner replaced all three fuel related relays, fuel pump, fuel filter, rotor, cap, plugs and wires -- all within the last couple of years according to the receipts.
Any ideas? Thanks in advance for your assistance!
The vehicle has been running seemingly fine since purchased, other than the fact that I've noticed it takes about three seconds of cranking before the engine fires up. It will stumble, but I can usually feather the throttle pedal to coax it along. Otherwise it will stall, and I'll have to re-crank once.
Ironically, I never hear a fuel pump kick in in the ignition start position like other cars -- is this normal?
Two days ago, I backed it out and gave it an exterior wash (again), cranked it back up and parked it without drama. Last night, I went to move it again and it would just crank but that's all. It's almost as if it's not getting any fuel delivery.
Today, I checked all the related relays and fuse in the panel, and they all look fine. The previous owner replaced all three fuel related relays, fuel pump, fuel filter, rotor, cap, plugs and wires -- all within the last couple of years according to the receipts.
Any ideas? Thanks in advance for your assistance!
03-03-2015, 06:28 PM
#2
First welcome! Second, how's the weather there? If it seems like a cold starting issue, (only when the engine is cold), Search for "temp sensors", there are a couple that are easy to replace but can really be a pain in the backside on cold starts. The checks can be done in the driveway with a meter. That should get ya "started" in the direction of eliminating issues since ya know it runs, and some of the important relays have been replaced. There are plenty of write-ups on the starting thing.
There could be a couple other things. You already touched on the fuel pump, and there is a check valve on the end of the pump to hold the fuel pressure at the ready for quick starts. But that mostly comes into play for "long cranks", not as much on "no starts" .
It may take a helper to hear the pump.
There could be a couple other things. You already touched on the fuel pump, and there is a check valve on the end of the pump to hold the fuel pressure at the ready for quick starts. But that mostly comes into play for "long cranks", not as much on "no starts" .
It may take a helper to hear the pump.
03-03-2015, 06:33 PM
#3
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The fuel pump does not run until the engine is cranking at 50 RPM or more. It does not start running when the ignition is turned on.
Rich
'93 GTS Covergirl
'87 S4 928
'79 5-speed rescue
'79 Euro 5-liter track beast
Rich
'93 GTS Covergirl
'87 S4 928
'79 5-speed rescue
'79 Euro 5-liter track beast
03-03-2015, 06:57 PM
#4
Team Owner
well since you have a 86 your going to have to pay attention to this lil tidbit,
and that is ,
you really should run the engine up to temperature every time you run the engine.
Doing the short run time sequences will usually result in a flooded engine and fouled plugs.
So from where you are now ,
check/ replace the fuel pump fuse,
remove the vacuum lines from the 2 dampers and the 1 fuel pressure regulator smell for fuel,
if you smell fuel then all 3 of these parts should be replaced.
Dont mess with the fuel pump relay yet...
then with a fully charged battery,
hold the pedal to the floor,
then crank it for 15 seconds,
hold the pedal to the floor till it starts to run.
Please Report your findings
and that is ,
you really should run the engine up to temperature every time you run the engine.
Doing the short run time sequences will usually result in a flooded engine and fouled plugs.
So from where you are now ,
check/ replace the fuel pump fuse,
remove the vacuum lines from the 2 dampers and the 1 fuel pressure regulator smell for fuel,
if you smell fuel then all 3 of these parts should be replaced.
Dont mess with the fuel pump relay yet...
then with a fully charged battery,
hold the pedal to the floor,
then crank it for 15 seconds,
hold the pedal to the floor till it starts to run.
Please Report your findings
Last edited by Mrmerlin; 03-03-2015 at 09:07 PM.
03-03-2015, 07:46 PM
#6
You guys even have my wife saying that.
I had a flat one day, the wife said ..."Relay, Relay, Relay".
I've had both the fuel pressure damper leaking fuel and the temp sensor failures...at the same time.
In the summer it would start great the first start of the day, or when it was cold...aided by the extra fuel in the vac lines from the leaky FPD/FPR. But when hot, or after just shutting it down, like at the gas station, it was hard to start (flooded from too much fuel in the VAC lines from a leaky FPD/FPR) I Found that by the smell in the vac line. (actually drips of fuel in the Vac line). Then after I eliminated the extra fuel in the vac lines, it didn't want to start on the cold mornings...and that turned out to be a temp sensor - found it by checking ohmic value with meter. It's pretty much a 1 crank starter now sun or snow. At one point the long cranking times had me chasing the check valve, (as if the pump had to build pressure before it would start) but in my case it was a non issue but it was easy to replace and I know it's good now.
I had a flat one day, the wife said ..."Relay, Relay, Relay".
I've had both the fuel pressure damper leaking fuel and the temp sensor failures...at the same time.
In the summer it would start great the first start of the day, or when it was cold...aided by the extra fuel in the vac lines from the leaky FPD/FPR. But when hot, or after just shutting it down, like at the gas station, it was hard to start (flooded from too much fuel in the VAC lines from a leaky FPD/FPR) I Found that by the smell in the vac line. (actually drips of fuel in the Vac line). Then after I eliminated the extra fuel in the vac lines, it didn't want to start on the cold mornings...and that turned out to be a temp sensor - found it by checking ohmic value with meter. It's pretty much a 1 crank starter now sun or snow. At one point the long cranking times had me chasing the check valve, (as if the pump had to build pressure before it would start) but in my case it was a non issue but it was easy to replace and I know it's good now.
Last edited by The Patman; 03-03-2015 at 10:41 PM.
03-03-2015, 09:09 PM
#7
Team Owner
my thought was, its either flooded or the fuel pump fuse is bad.
If that is the case, then doing what was suggested will find the culprit.
If it wont start with the above suggestions then we must move on to the relays
If that is the case, then doing what was suggested will find the culprit.
If it wont start with the above suggestions then we must move on to the relays
Last edited by Mrmerlin; 03-04-2015 at 08:08 AM.
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03-03-2015, 11:54 PM
#8
Rennlist Member
How old is the batt?
A rare 928 that doesn't need a maintainer on it. You've had it 3 weeks. A new batt and a DVM is usu the first purchase for a new owner.
Sharks need a strong 12.5v and good grounds, plural.
And a DVM may not tell you if you have a bad cell. A load test is the only thing that will tell you.
A rare 928 that doesn't need a maintainer on it. You've had it 3 weeks. A new batt and a DVM is usu the first purchase for a new owner.
Sharks need a strong 12.5v and good grounds, plural.
And a DVM may not tell you if you have a bad cell. A load test is the only thing that will tell you.
03-04-2015, 11:08 AM
#9
Rennlist Member
It can't hurt to open up the battery box and make sure that the secondary wire which attaches to the side of the positive terminal connector is on there securely. Mine was loose and a little corroded, causing intermittent no-starts and stalls. This wire feeds the fuel pump, among (maybe) a few other things...
03-04-2015, 11:09 AM
#10
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Thank you for the kind welcome and for all the quick replies and excellent information thus far -- most of which I didn't even know about regarding how these 928's operate during startup.
I will check out the components that you suggested, and replace as necessary -- especially for 'peace of mind'.
Update on the situation: I accessed the battery last night in order to verify type / dimensions in case a new one is in order. Will probably replace the ground strap while in there. Afterwards, I put the BatteryTender trickle charger on it -- connected to the positive jump post and cross-brace ground under the front hood -- and let it charge overnight. This morning, all was 'green' so I hopped in and turned the key. It fired right up and ran just fine.
So, it appears that a new battery might be necessary (don't know when the last one was put in), and then go from there checking other items that you've suggested. Also, would it be wise to have the alternator regulator / brushes inspected?
Think you're right about the short runs, and not getting the car fully up to temp. My commute to work and back is only about 2 miles one way -- might need to take the long way home.
Any further ideas or suggestions are fully welcome! Thanks again...
EDIT: Forgot to mention -- I did noticed when cranking it up this morning that the voltage gauge was pegged at the bottom with a small red light illuminated below the needle when the key was in the start position. Even after it started, the needle stayed at the bottom but the light went out. Would this be cause for concern or just a bad gauge?
I will check out the components that you suggested, and replace as necessary -- especially for 'peace of mind'.
Update on the situation: I accessed the battery last night in order to verify type / dimensions in case a new one is in order. Will probably replace the ground strap while in there. Afterwards, I put the BatteryTender trickle charger on it -- connected to the positive jump post and cross-brace ground under the front hood -- and let it charge overnight. This morning, all was 'green' so I hopped in and turned the key. It fired right up and ran just fine.
So, it appears that a new battery might be necessary (don't know when the last one was put in), and then go from there checking other items that you've suggested. Also, would it be wise to have the alternator regulator / brushes inspected?
Think you're right about the short runs, and not getting the car fully up to temp. My commute to work and back is only about 2 miles one way -- might need to take the long way home.
Any further ideas or suggestions are fully welcome! Thanks again...
EDIT: Forgot to mention -- I did noticed when cranking it up this morning that the voltage gauge was pegged at the bottom with a small red light illuminated below the needle when the key was in the start position. Even after it started, the needle stayed at the bottom but the light went out. Would this be cause for concern or just a bad gauge?
Last edited by Eric85.5944NA; 03-04-2015 at 11:16 AM. Reason: Forgot to mention
03-04-2015, 11:35 AM
#11
So the light went out...but even with the car at idle...running...the needle is at the bottom?
Yes ...cause for concern. But easy to investigate.
When we're running, and the light is out, put a DVM (multi meter) on either the battery post which is my favorite place (positive and ground of course) or the jumper post in the engine bay and ground, and look for 13.5 to 14 volts. I like the battery post (and not the cable, the post) cause this makes sure the charge is going all the way back to the battery, and going through the cable to the actual post.
If you have it at the battery, then it may be just a indicator or wire issue.
Yes ...cause for concern. But easy to investigate.
When we're running, and the light is out, put a DVM (multi meter) on either the battery post which is my favorite place (positive and ground of course) or the jumper post in the engine bay and ground, and look for 13.5 to 14 volts. I like the battery post (and not the cable, the post) cause this makes sure the charge is going all the way back to the battery, and going through the cable to the actual post.
If you have it at the battery, then it may be just a indicator or wire issue.
03-04-2015, 11:36 AM
#12
Nordschleife Master
The voltmeters are notoriously unreliable.
The best way to check is with a multimeter. Get a real reading.
These cars also are notorious for having parasitic battery drains.
They aren't supposed to be pulling a lot of amps out of the battery when shut off, but they often do. There are a number of ways to check this out, and a variety of ways for the car to drain your battery.
Edit to add: Patman beat me to it.
The best way to check is with a multimeter. Get a real reading.
These cars also are notorious for having parasitic battery drains.
They aren't supposed to be pulling a lot of amps out of the battery when shut off, but they often do. There are a number of ways to check this out, and a variety of ways for the car to drain your battery.
Edit to add: Patman beat me to it.
03-04-2015, 11:46 AM
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EDIT: Forgot to mention -- I did noticed when cranking it up this morning that the voltage gauge was pegged at the bottom with a small red light illuminated below the needle when the key was in the start position. Even after it started, the needle stayed at the bottom but the light went out. Would this be cause for concern or just a bad gauge?
03-04-2015, 12:16 PM
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I'll check things out with a multi-meter and report back -- should be easy while the battery is still exposed. Did not know that about blipping the throttle either to energize the alt. circuit.
Also forgot to mention earlier that the temperature here in FL over the past few days has been in the high 70's to low 80's -- in reference to The Patman's question.
If a new battery is in order, I found a source locally for an Interstate Mega-Tron-Plus 93 with 850 CCA's that is the same dimensions as the existing one.
Also forgot to mention earlier that the temperature here in FL over the past few days has been in the high 70's to low 80's -- in reference to The Patman's question.
If a new battery is in order, I found a source locally for an Interstate Mega-Tron-Plus 93 with 850 CCA's that is the same dimensions as the existing one.
04-01-2015, 02:37 PM
#15
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Just a quick follow up to everything thus far...
Ended up installing a new Interstate MTP49/H8 battery three weeks ago. Also had them do a quick electrical check on the alternator and starter, and they said all the readings were within range...whatever that means.
Immediately, things like the central locking system started working again. When I turned the key, instead of hearing 3 seconds of womp-womp-womp, I was greeted with a very quick starter engagement / engine crank. Also, the volt gauge needle shows a steady reading between 13 &14, instead of bouncing around like before.
After driving the vehicle for a couple of days, it then sat over the weekend. Afterwards, when I went to crank it up, it would just crank and crank without the engine firing up. So, I put the battery tender on it for a day and it fired right up after that. This would be on the new battery.
Got to researching some threads on here trying to narrow it down. Was also going to begin troubleshooting many of the items that you all have suggested. Then I stumbled across the following thread: https://rennlist.com/forums/928-foru...remove-it.html
Sure enough, I had one of these same exact disconnects in the rear hatch hidden behind the tool panel under the carpet. After removing it and reconnecting the ground strap directly to the chassis, I haven't had any issues with starting the car since.
I'm still going to double-check all the items that everyone mentioned as soon as I get the chance, and will post another follow up. Thanks for your help so far!
Ended up installing a new Interstate MTP49/H8 battery three weeks ago. Also had them do a quick electrical check on the alternator and starter, and they said all the readings were within range...whatever that means.
Immediately, things like the central locking system started working again. When I turned the key, instead of hearing 3 seconds of womp-womp-womp, I was greeted with a very quick starter engagement / engine crank. Also, the volt gauge needle shows a steady reading between 13 &14, instead of bouncing around like before.
After driving the vehicle for a couple of days, it then sat over the weekend. Afterwards, when I went to crank it up, it would just crank and crank without the engine firing up. So, I put the battery tender on it for a day and it fired right up after that. This would be on the new battery.
Got to researching some threads on here trying to narrow it down. Was also going to begin troubleshooting many of the items that you all have suggested. Then I stumbled across the following thread: https://rennlist.com/forums/928-foru...remove-it.html
Sure enough, I had one of these same exact disconnects in the rear hatch hidden behind the tool panel under the carpet. After removing it and reconnecting the ground strap directly to the chassis, I haven't had any issues with starting the car since.
I'm still going to double-check all the items that everyone mentioned as soon as I get the chance, and will post another follow up. Thanks for your help so far!