Will crank but won't start intermittently
#1
Rennlist Member
Thread Starter
Will crank but won't start intermittently
I've had the 928 now for about a month now. Every once in a while the car will crank but not start. The car seems like it just isn't getting fuel. It cranks strongly but just won't turn over & catch. I will come back later & it will catch on the first crank. Any thoughts on where to start...fuel filter, fuel pump.
Wanted to take the car & wife out tonight for dinner in the 928. Cranked it for a couple of minutes to no avail. We came home & she cranked/started on the first try.
Thx Todd
Wanted to take the car & wife out tonight for dinner in the 928. Cranked it for a couple of minutes to no avail. We came home & she cranked/started on the first try.
Thx Todd
#2
Rennlist Member
Wow, that's a beautiful looking car!
First thing I would do is the least expensive stuff. Clean the ground points, especially back in the battery box and the large ground cable in the lower engine bay, passenger side, that ties into the engine block. Dirty or corroded grounds could cause this issue. Also, try swapping out the fuel pump relay. That could be the issue too. With an 86, you can use the horn relay to test. A relay that is going bad can cause this issue too.
After that, it could be a number of things, like a fuel pump going bad, and ISV going bad, and so forth. Do the easy stuff first to rule it out.
First thing I would do is the least expensive stuff. Clean the ground points, especially back in the battery box and the large ground cable in the lower engine bay, passenger side, that ties into the engine block. Dirty or corroded grounds could cause this issue. Also, try swapping out the fuel pump relay. That could be the issue too. With an 86, you can use the horn relay to test. A relay that is going bad can cause this issue too.
After that, it could be a number of things, like a fuel pump going bad, and ISV going bad, and so forth. Do the easy stuff first to rule it out.
#3
Rennlist Member
One other thing, check the fuel pump fuse too (get the fuse chart for your car off the 928 Specialist site). If it looks like it is burned at the connections, that would be a sign of a fuel pump going bad. Note, the lack of burn marks around the fuse is not a diagnosis that the pump is good, however.
#6
Rennlist Member
Does the tach bounce when it doesn't start? My crank position sensor was failing intermittently, I had changed relays, cleaned grounds and still had intermittent start issues. One day, realized the tach wasn't moving while cranking. Changed the CPS and haven't had a problem since.
#7
Yes to all the above suggestions. These cars are very reliableconsidering age as long as (likely) over due maintenance is done. Unfortunately, that catchup may involve spending a few bucks at the front end.
1) get a fuel pressure gauge with a hose attachment that you can temporarily clamp on the front fuel rail. Temporarily Insert a jumper in place of the fuel pressure relay. Check your fuel pressure. If it's in spec, then put that concern to rest for a bit.
2) if you don't know the life of your principle relays ( fuel pump, ezk, lh) then replace them. They aren't expensive for your car. Replace ALL of the fuses. It's not expensive either. Spray de-oxit into the receptacles of all of the relay and fuse sockets before reinserting relays/fuses.
3) very carefully examine the engine bay flexible fuel lines. If there is any doubt about their condition, replace them.
4) if you don't know the life of your fuel pressure regulators/dampeners, replace them. As mentioned, these can easily cause your symptoms.
5) if you don't know the life of your crank position sensor, replace it. Symptoms same as item 4 above
5a) check condition of all your vacuum hoses under the intake manifold. Replace any that are if questionable condition.
Note: items 3,4,5, 5a) above are best all done AT THE SAME time. So, it's all while-you-are-in-there stuff.
6) clean up ALL your ground points. Ground point maps are available via forum search and forum readers can tell you where to buy the manual cds. Clean your battery posts and clamps. Clean your battery ground to body quick release ends. Disconnect, clean with de-oxit and reconnect the cable harness connections under your dash pod.
7) cleanup/polish the power/ground connections at your passenger front fender well. Clean the multi contact power plug also on your right front fender with deoxit.
Get the parts for the above and you have a busy Saturday morning job to wrap it up. These things stand a good chance of rectifying most causes of your symptoms.
Put things on your todo list going forward. Every spring should include some kind of refresh, so you can drive it the rest of the year. Bear in mind, your car and my car are both now 30 years old. Plan on spending about 1k per year on refresh projects. Maybe more for a few years, if your car is behind on updates.
Best of luck!
1) get a fuel pressure gauge with a hose attachment that you can temporarily clamp on the front fuel rail. Temporarily Insert a jumper in place of the fuel pressure relay. Check your fuel pressure. If it's in spec, then put that concern to rest for a bit.
2) if you don't know the life of your principle relays ( fuel pump, ezk, lh) then replace them. They aren't expensive for your car. Replace ALL of the fuses. It's not expensive either. Spray de-oxit into the receptacles of all of the relay and fuse sockets before reinserting relays/fuses.
3) very carefully examine the engine bay flexible fuel lines. If there is any doubt about their condition, replace them.
4) if you don't know the life of your fuel pressure regulators/dampeners, replace them. As mentioned, these can easily cause your symptoms.
5) if you don't know the life of your crank position sensor, replace it. Symptoms same as item 4 above
5a) check condition of all your vacuum hoses under the intake manifold. Replace any that are if questionable condition.
Note: items 3,4,5, 5a) above are best all done AT THE SAME time. So, it's all while-you-are-in-there stuff.
6) clean up ALL your ground points. Ground point maps are available via forum search and forum readers can tell you where to buy the manual cds. Clean your battery posts and clamps. Clean your battery ground to body quick release ends. Disconnect, clean with de-oxit and reconnect the cable harness connections under your dash pod.
7) cleanup/polish the power/ground connections at your passenger front fender well. Clean the multi contact power plug also on your right front fender with deoxit.
Get the parts for the above and you have a busy Saturday morning job to wrap it up. These things stand a good chance of rectifying most causes of your symptoms.
Put things on your todo list going forward. Every spring should include some kind of refresh, so you can drive it the rest of the year. Bear in mind, your car and my car are both now 30 years old. Plan on spending about 1k per year on refresh projects. Maybe more for a few years, if your car is behind on updates.
Best of luck!
Last edited by mj1pate; 04-04-2016 at 05:29 PM.
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#8
Rennlist Member
Thread Starter
Thanks guys. I will explore each of these. I realize the car is 30 years old & thankfully I have the financial ability to bring the car back & do the things that need to be done. The prior two owners also were fastidious about maintaining the 928 so it isn't too daunting.
We also have a 1986 911 Cabriolet that we are good stewards of. We realize that we are only owning them for a period of time & make sure that the next person has an even nicer car than when I bought it !!
#9
Racer
Join Date: Aug 2011
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Hey Todd, great set of motors!
I would look at crank reference sensor on top of bell housing. You can access below air box under the firewall. This goes flakey from heat, especially the wiring connections. The engine will crank over normally and not catch. Starts intermitant, but will ultimately leave you stranded!
If it hasn't been changed in its life, you will need to ultimately.
I would look at crank reference sensor on top of bell housing. You can access below air box under the firewall. This goes flakey from heat, especially the wiring connections. The engine will crank over normally and not catch. Starts intermitant, but will ultimately leave you stranded!
If it hasn't been changed in its life, you will need to ultimately.
#10
This is just a typical 928...doesn't start when you want it to, but runs when you don't really care if it starts or not.
They're kind of like women, the more you pursue them...the more difficult they can be. But, if you play it cool and act like you don't give a crap...they are like puddy in your hands.
So, the next time you really, really want to drive the car...just pertend like it doesn't matter...and I guarantee you...it will start up like a champ. Now, once inside...don't let on about what you've done...or this will only work that one time. These cars are extremely smart...and that is what makes them somewhat like men.
Brian.
They're kind of like women, the more you pursue them...the more difficult they can be. But, if you play it cool and act like you don't give a crap...they are like puddy in your hands.
So, the next time you really, really want to drive the car...just pertend like it doesn't matter...and I guarantee you...it will start up like a champ. Now, once inside...don't let on about what you've done...or this will only work that one time. These cars are extremely smart...and that is what makes them somewhat like men.
Brian.
#11
Rennlist Member
Alarm system? My 79 factory alarm would do this all too often till I bypassed it. Would turn over with no hint of a start because it had no spark.
Next time this happens lock and unlock drivers door with key and try again.
Next time this happens lock and unlock drivers door with key and try again.
#12
Rennlist Member
This is just a typical 928...doesn't start when you want it to, but runs when you don't really care if it starts or not.
They're kind of like women, the more you pursue them...the more difficult they can be. But, if you play it cool and act like you don't give a crap...they are like putty in your hands.
So, the next time you really, really want to drive the car...just pertend like it doesn't matter...and I guarantee you...it will start up like a champ. Now, once inside...don't let on about what you've done...or this will only work that one time. These cars are extremely smart...and that is what makes them somewhat like men.
Brian.
They're kind of like women, the more you pursue them...the more difficult they can be. But, if you play it cool and act like you don't give a crap...they are like putty in your hands.
So, the next time you really, really want to drive the car...just pertend like it doesn't matter...and I guarantee you...it will start up like a champ. Now, once inside...don't let on about what you've done...or this will only work that one time. These cars are extremely smart...and that is what makes them somewhat like men.
Brian.
#14
6th Gear
My 84 has the same issue. Very irritating to say the least. In the garage is also my 85 Mazda RX-7, both of which I start once a month. The Mazda always takes several cranks by nature to start but always does eventually. The 928, starts and sometimes just sits and cranks sounding like...nyah, nyah, nyah, nyah...nyah, nyah, nyah, nyah! It's a crap shoot, after all the work I've done on it this is how it repays me? Just ranting.
#15
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My 84 has the same issue. Very irritating to say the least. In the garage is also my 85 Mazda RX-7, both of which I start once a month. The Mazda always takes several cranks by nature to start but always does eventually. The 928, starts and sometimes just sits and cranks sounding like...nyah, nyah, nyah, nyah...nyah, nyah, nyah, nyah! It's a crap shoot, after all the work I've done on it this is how it repays me? Just ranting.
I have cleaned the battery grounds and strap, changed fuel pump fuse, starter, fuel injection and fuel pump realy, fuel dampener, spark plug wires 5 years old, caps and rotor newish, 14 pins connection checked, also new alternator.....now starts at first crank even in winter once a month start