944S start run issues
#1
944S start run issues
OK, seems like I need to be added to list of those suffering starting issues. I've reviewed several threads & Clark's Garage site. I am an old-school, distributor/carburetor guy and am rather intimidated by vacuum hoses, electrical sensors & DME associated bits.
Quick data point is engine starts when starter fluid is sprayed into the Air Fuel Meter.
I am reluctant to remove intake manifold to gain access to various temperature & reference sensors.
Fuel pump is audible but I haven't checked injector spray patterns.
Actually car has behaved well but a couple of times it just quit while driving and once it hesitated a couple of times while driving. It ran flawlessly during a 120 mile round trip to DE at Portland International Raceway. Therefore I assume it to be an intermittent electrical connection.
Any sage advice as to:
Quick data point is engine starts when starter fluid is sprayed into the Air Fuel Meter.
I am reluctant to remove intake manifold to gain access to various temperature & reference sensors.
Fuel pump is audible but I haven't checked injector spray patterns.
Actually car has behaved well but a couple of times it just quit while driving and once it hesitated a couple of times while driving. It ran flawlessly during a 120 mile round trip to DE at Portland International Raceway. Therefore I assume it to be an intermittent electrical connection.
Any sage advice as to:
- where to look first
- should I remove intake manifold to access sensors
#2
Nordschleife Master
I take it that it's not starting. You imply that but don't actually state it in your post.
If it runs on starting fluid, the crank sensors are working. It indicates everything is working but fuel.
My next move would be to put a noid light on the injector 'plug ins' (where the harness plugs into the injector). If you don't have one, the major parts chains usually have then in their 'loan a tool' program.
That tells you if you are getting injector pulse or not.
That info will tell you where to go next.
If it runs on starting fluid, the crank sensors are working. It indicates everything is working but fuel.
My next move would be to put a noid light on the injector 'plug ins' (where the harness plugs into the injector). If you don't have one, the major parts chains usually have then in their 'loan a tool' program.
That tells you if you are getting injector pulse or not.
That info will tell you where to go next.
#3
Yes, won't start now.
First time it happened was in 2016 and then last week. There was one situation where the engine hiccuped a couple of times. I found a broken connector at back of engine bay that I thought was providing faulty connection and after I secured the connection (2016) the issue seemed to be resolved...until last week. I agree it to be a fuel delivery issue since it starts with starting fluid.
I just ordered a noid light kit so perhaps I will know more in a few days.
First time it happened was in 2016 and then last week. There was one situation where the engine hiccuped a couple of times. I found a broken connector at back of engine bay that I thought was providing faulty connection and after I secured the connection (2016) the issue seemed to be resolved...until last week. I agree it to be a fuel delivery issue since it starts with starting fluid.
I just ordered a noid light kit so perhaps I will know more in a few days.
#6
Drifting
Your noid light kit quite possibly won't have the right light: ask me how I know. If not, go to an electronics supply or order online a basic 12v LED
Pulling the fuel rail? Make sure you have new o-rings (if not recently serviced). Sure, it's "easy", relatively, but you may find it interesting to put back. Take pics of the clip locations
Pulling the fuel rail? Make sure you have new o-rings (if not recently serviced). Sure, it's "easy", relatively, but you may find it interesting to put back. Take pics of the clip locations
Trending Topics
#9
Drifting
Yes and no; removing the fuel rail (and re-installing) can be much more involved than hooking up a light. Search fuel injector install threads and you'll see.
The LED method is excellent: easy and quick. In fact, that little LED can be used in many places for quick feeback, including at the coil, DME, etc. Find one!
The LED method is excellent: easy and quick. In fact, that little LED can be used in many places for quick feeback, including at the coil, DME, etc. Find one!
Last edited by Dan Martinic; 10-25-2018 at 03:03 PM. Reason: Grammar
#10
Rennlist Member
To pull the fuel rail up, you'll have to unbolt the fuel damper from the front of the intake manifold and you'll have to unplug to vacuum line to the fuel regulator (by the oil fill). Unbolt the fuel rail, and then with a prybar, lever the 1st injector out of the intake manifold - once it starts coming out, the others will follow.
#11
Drifting
place each injector in a cup, crank engine for x seconds, then observe how much fuel is in each cup. There should be equal amounts.
If no fuel in a cup, switch a "good" injector with a "bad" injector. If the good ingector works in the bad injector location and the bad ingector placed in the good injector position shows bad, then the fuel harness is OK.
If there is not uniform amount of fuel collected, then. injectors should be cleaned. A good vendor is BayShore Fuel Injector Service
If no fuel in a cup, switch a "good" injector with a "bad" injector. If the good ingector works in the bad injector location and the bad ingector placed in the good injector position shows bad, then the fuel harness is OK.
If there is not uniform amount of fuel collected, then. injectors should be cleaned. A good vendor is BayShore Fuel Injector Service
#12
I just performed fuel output pressure check & no pressure. Clark's Garage has a procedure to follow now that fuel delivery is the suspect. I suspect an electrical issue associated with the pump since pressure is zero. A dying pump would not seize up & stop, it would provide diminished pressure. An intermittent electrical issue would explain why engine would run after similar failure a couple of years ago but a failed pump would remain failed.
#13
Nordschleife Master
#14
I'm an old points and carburetor guy myself so I too have felt your pain, but patience Grasshopper, it's not that bad to adapt too. I hate to ask such a simple question but have you tried a different DME relay? It's the second step on a no start, the first being the jiggling of the aforementioned speed and reference sensor connections.
#15
I jumped the 30 & 87b terminals where the DME relay goes per Clark's Garage and no pressure but I did note the power was delivered to the pump since the trickle charger that I had hooked up jumped in power draw. I plan to directly apply 12VDC to pump terminals as my next course of action.
Engine did start when cranked with starter fluid sprayed into the AFM so other electrical ills seem to be off the table for now.
Curious to me how fuel pump ran well for a couple of years before this episode re-occured. Car is not driven much but is driven enough to keep it active.
Possibly the fuel filter is clogged which would stop fuel delivery even if pump is working OK. Perhaps the DE shook up some crud that finally clogged the filter? My dearly departed SWB 911 hot rod offered that lesson to me...said the Grasshopper.
Thanks to all for the input.
Engine did start when cranked with starter fluid sprayed into the AFM so other electrical ills seem to be off the table for now.
Curious to me how fuel pump ran well for a couple of years before this episode re-occured. Car is not driven much but is driven enough to keep it active.
Possibly the fuel filter is clogged which would stop fuel delivery even if pump is working OK. Perhaps the DE shook up some crud that finally clogged the filter? My dearly departed SWB 911 hot rod offered that lesson to me...said the Grasshopper.
Thanks to all for the input.