87 S4 Car wont start unless I pump gas pedal
#1
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I have an 87 Auto and 9 out of 10 times, the car won't start without a couple of pumps of the gas pedal or holding down the pedal. This happens regardless if its cold or hot. Once started, it idles smoothly and runs fairly well so it doesn't sound like a vacuum leak.
I did some research and thought it was a cold start valve issue but read on other posts that the 87 doesn't have one. One another post I read stated it could be a temp II sensor. Any thoughts on what I should check?
Thanks a bunch,
Ather
I did some research and thought it was a cold start valve issue but read on other posts that the 87 doesn't have one. One another post I read stated it could be a temp II sensor. Any thoughts on what I should check?
Thanks a bunch,
Ather
#2
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Pressing the pedal opens the throttle valve but doesnt inject fuel.........is it running rich? bad gas mileage?
Id run a diagnosis on the sensors if the cpus have updated eproms, if not hen its the old fashioned way with an ohm meter.
Id run a diagnosis on the sensors if the cpus have updated eproms, if not hen its the old fashioned way with an ohm meter.
#3
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Apologies for my ignorance but not sure what running rich means. If it means using more fuel than normal, I think it is but not 100% sure. It has always been this way since I have owned the car for the last 6 months.
Also don't know what I should be checking using the Ohm meter or how to run a diagnosis on the sensors. I will look that up and see what I can find. Thx.
Also don't know what I should be checking using the Ohm meter or how to run a diagnosis on the sensors. I will look that up and see what I can find. Thx.
#4
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ok.....good to know where we're at
the temp II sensor does tell the fuel injection computer what the coolant temp is which is interpreted by sending the injectors info............if this is inaccurate then yes you may have starting issues; cold or hot.
to test first locate the sensor on the water bridge at the front of the engine left hand side when standing in front of the car (#11). the sensor has 2 electrical leads which should be discoonected and readings taken between one of the sensor connectors and ground at several different engine temps.
If you first locate it remove the wires and see if the car starts.....it shouldnt![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
do you have a good ohm meter and know how it operates?
the temp II sensor does tell the fuel injection computer what the coolant temp is which is interpreted by sending the injectors info............if this is inaccurate then yes you may have starting issues; cold or hot.
to test first locate the sensor on the water bridge at the front of the engine left hand side when standing in front of the car (#11). the sensor has 2 electrical leads which should be discoonected and readings taken between one of the sensor connectors and ground at several different engine temps.
If you first locate it remove the wires and see if the car starts.....it shouldnt
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
do you have a good ohm meter and know how it operates?
Last edited by the flyin' scotsman; 10-29-2011 at 08:04 PM. Reason: add pic
#5
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Hi, and thanks for help.
I disconnected what I think is the temp sensor and tried starting it and it started without even pressing the gas..go figure. So if it is not supposed to start, it did. Not sure what that means![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
I will pick up an Ohm meter and test the pins to see if there is is resistance shortly.
I disconnected what I think is the temp sensor and tried starting it and it started without even pressing the gas..go figure. So if it is not supposed to start, it did. Not sure what that means
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
I will pick up an Ohm meter and test the pins to see if there is is resistance shortly.
#6
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Ather--
Your symptoms often point to a leaking fuel pressure regulator or damper. After the car has run a bit, pull ff the vacuum hose to each and sniff that hose for fuel smell. If there's any, the damper or regulator is leaking.
Also, VERY IMPORTANT that you get the right fuel hose for the car. Your picture shows a section of fabric braid-covered hose for the crossover between the front damper and the other fuel rail. Has repair clamps on it. This and the other hose in the fuel system must be correct, and need to be replaced due to age. That questionable repair in the front hose would ignite my interest a lot if it were my car. If it isn't FI-rated hose it's time to replace it before you drive it.
Your symptoms often point to a leaking fuel pressure regulator or damper. After the car has run a bit, pull ff the vacuum hose to each and sniff that hose for fuel smell. If there's any, the damper or regulator is leaking.
Also, VERY IMPORTANT that you get the right fuel hose for the car. Your picture shows a section of fabric braid-covered hose for the crossover between the front damper and the other fuel rail. Has repair clamps on it. This and the other hose in the fuel system must be correct, and need to be replaced due to age. That questionable repair in the front hose would ignite my interest a lot if it were my car. If it isn't FI-rated hose it's time to replace it before you drive it.
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thats the tempII arrowed in the pic bur as Dr bob suggest s you may have many more issues...........the black paint on the intake and the wiring on the water temp guage sensor are non stock.......did the car have an intake R&R?
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#8
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Hi Dr. Bob, thanks very much for pointing that out. Didn't know it was an issue.
I know what the Fuel Pressure Regulator is but don't know what/where the damper is (still learning the mechanical terms). I have smelled fuel on occasion.
I'll get the fuel hose replaced right away.
Thanks again.
Cheers,
Ather
I know what the Fuel Pressure Regulator is but don't know what/where the damper is (still learning the mechanical terms). I have smelled fuel on occasion.
I'll get the fuel hose replaced right away.
Thanks again.
Cheers,
Ather
#9
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Don't know for sure but I will be doing one anyway in the near future. I bought it off a guy who purchased it from an Insurance Auction and did some limited repair from a minor engine fire. There was no history on it. I will also replace the the temp sensor to the stock one as well.
#10
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ok.....given htta one hose is a major hazard there may be others...........Id park the car and inspect all hoses and fuel related items before proceeding any further.
If you take the intake filter housing off we'll have a far better idea of state of affairs at the back of the engine.
If you take the intake filter housing off we'll have a far better idea of state of affairs at the back of the engine.
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There is two fuel pressure dampners on your car.
One in front of the engine (to the right of the oil filler neck, you can see it in the picture) and one in the back of the engine behind the driver's valve cover.
As it starts better with the temperature sensor disconnected, check that first.
Let us know what you will find.
One in front of the engine (to the right of the oil filler neck, you can see it in the picture) and one in the back of the engine behind the driver's valve cover.
As it starts better with the temperature sensor disconnected, check that first.
Let us know what you will find.
#12
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Hi Bertrand,
I don't know what I am supposed to be looking for. Can you describe it to me?
Is it s something I should change along with the fuel lines too?
Thanks very much,
I don't know what I am supposed to be looking for. Can you describe it to me?
Is it s something I should change along with the fuel lines too?
Thanks very much,
#13
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The dampers and the regulator look very similar. In your picture, the front damper is on the right end of the fuel hose I mentioned. So one side attaches to the driver's side rail in front, gets the fuel supply line in from the bottom, has the port for that fabric hose going to the other rail, and has a small vacuum hose plugged into the top. The sniff test there is a first-check, with a leak confirmed with a small hand vacuum checker like a MitiVac. If it doesn't hold vacuum, it needs a new one.
There's another damper on the rear of that driver's side fuel rail, with a U-shaped hose passing under the throttle linkage to the pressure regulator at the rear of the passenger's side fuel rail. The regulator has the return line to the tank along with the connections from each rail and the vacuum hose.
Since you had a fire, it's likely a fuel hose that failed. Seeing the possibly marginal hose on the front, the car needs a good inspection of the other hoses to make sure that they have the right hoses in there. Roger at 928SRUS has a kit of all the engine bay hoses that might be the safest route to go. Lots of other things to get for your intake refresh project too I'm sure.
There's another damper on the rear of that driver's side fuel rail, with a U-shaped hose passing under the throttle linkage to the pressure regulator at the rear of the passenger's side fuel rail. The regulator has the return line to the tank along with the connections from each rail and the vacuum hose.
Since you had a fire, it's likely a fuel hose that failed. Seeing the possibly marginal hose on the front, the car needs a good inspection of the other hoses to make sure that they have the right hoses in there. Roger at 928SRUS has a kit of all the engine bay hoses that might be the safest route to go. Lots of other things to get for your intake refresh project too I'm sure.
#15
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Okay I picked up a multi-meter and
tested the temp II sensor. I set the resistance to 20k and got 2.5 on pin 2 and 2.4 on pin 1.
According to the WSM it says for LH fuel injection (guessing that is what I have since it is an 87) 15 C - 30 C should be 1.4 to 3.6k Ohms. If I read the results correctly, it sounds like it is in line with what I should expect, therefore the temp II sensor should be working. Did I read that correctly?
For the vacuum check on the damper, should I take the small rubber hose on top of it off and connect a small vacuum gauge there? It should hold pressure correct?
Thanks very much.
Ather
tested the temp II sensor. I set the resistance to 20k and got 2.5 on pin 2 and 2.4 on pin 1.
According to the WSM it says for LH fuel injection (guessing that is what I have since it is an 87) 15 C - 30 C should be 1.4 to 3.6k Ohms. If I read the results correctly, it sounds like it is in line with what I should expect, therefore the temp II sensor should be working. Did I read that correctly?
For the vacuum check on the damper, should I take the small rubber hose on top of it off and connect a small vacuum gauge there? It should hold pressure correct?
Thanks very much.
Ather