Greg86andahalf

In my other fuel injected cars and trucks, I do not have to press the accelerator to cold start them. In fact, I have always beleived that F/I cars should not have to be "pumped" or any gas given to start them.

My 86.5 928 however, will not start unless I feather the accelerator a bit. It Idles rough ad needs help for about 15 seconds than it will hold it's own.

I don't like the idea of even a mild "varoom" when the engine is cold and the oil has not circulated.

I'm thinking fuel pressure.

Any help would be appreciated.

Greg

Ed Ruiz

The fuel and ignition brains on a 86.5 928S may take a second or two to establish the proper fuel mixture and timeing, but it does not require priming. If you have to press the accelerator to get it to start, then something is wrong. :^(

My SWAG is that the fuel pressure regulator or one or both of the fuel pressure dampers is/are defective. An easy way to tell if they are bad is to pull off the attached vacuum line while the engine is running. If fuel squirts or trickles out, then the diaphram is ruptured and the unit is no longer functioning properly.

~ Merry motoring ~

Steve J.

Fuel pump check valve defective?

Steve Cattaneo

Greg
No, low or no fuel pressure when cold- drain back valve leaking. Check the fuel pressure.

Temp. II sensor – LH provides a rich mixture on cold start up. The temp.II Sensor is two sensors in one, pin #1 LH control- fuel, pin #2 EZFcontrol- timing.
You can ground each pin at the harness (to ground) if the car starts cold, bad sensor.
I would change it anyway (important input sensor).

The Throttle by pass valve is open on a cold engine, airflows from the throttle housing directly into the spider (air distributor). Check for 12V between the terminals. Or bad valve.
Other causes, bad grounds, idle speed low.

Steve C
The Great White
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Thom1

Hi Greg,

The Owner's Manual states that:

"Temperature sensors on the engine automatically provide the correct fuel/air mixture required for starting.

Therefore, it is not necessary to depress the accelerator pedal while starting a cold or warm engine."

My years of experience cause me typically to depress the accelerator pedal for the first time as soon as the car fires-up, especially when it is cold, or has not been started for a while. As soon as it fires-up, to me, means that it has started. On very rare occasions, the computer or something gets confused. Then it might take several tries to start the engine. Then I usually work the accelerator before it fires continuously. On some extremely rare occasions, after many tries to start the car, I have held the accelerator pedal to the floor while cranking until it fires. Then I would milk the pedal until it evens out. This has only happened about once a year. When warm, the car usually requires little or no pedal to start.

Here are some additional hints for avoiding starting problems:

Starting Problem:

When I was fixing valves, the most suspicious thing I found was a broken coil ground cable. Now that I am back up and running, there is no more starting problem. Here is what I did, and you can do: Clean the distributor cap and rotor contacts with a point file. Check or replace 2 coil ground cables. (Right side cable goes from coil bracket bolt to topmost front timing belt cover bolt. Left side connects at bottom rear of back timing belt cover.) Check engine ground wire about a foot forward of firewall, and a foot deep on right hand fender well. Scotch Bright all male blades of engine compartment electrical connections. Cycle blades in and out several times to clean female sides. A small round file works on some round female connections. I sealed ignition wires and distributors with Coastal Ignition Sealer from Autozone. Check their condition before you pull all the wires – too much work. I saw an ignition wire tester at Autozone. Clean your battery terminals… Believe it or not, that can be the culprit with no crank sound.

HTH,
Good Luck, <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />

Greg86andahalf

And the oscar goes to............

Ed.

I found that the fuel damper small vacuum nipple was bent and facing straight down. The PO gave me a spare crank TDC sensor and it is my guess that he must have unknowingly bent the nipple while changing the TDC sensor. The nipple was leaking vacuum. I did a "quick and dirty" fix to the nipple which sealed the leak. The damper now holds vacuum.

The car started with no pedal even with the air cleaner box off. I left the box off so I could check for fuel leaks at the damper since I had r/r'd it. I will have to wait a day now that it is all buttoned up to see if it starts when cold.

I'll post an update in a few days.

I will also do the maintenence that thomhross and steve recomend.

Thanks all.

Brett Matthews

This is interesting. I was near to posting of a similar problem. Glad you brought it up, Greg!

Last year, when we first bought our shark, it would start up, w/o any throttle application.

Then, I had a problem with what turned out to be a relay on the fuse board, someone from one of the big 3 told me which four relays had to work, to get the car to run, followed his step-by-step suggestions, worked great, 'cause when I got to the third relay, fired right up, and has started evr since.

Except for the fact that now, when it has sat overnight, I must push the gas pedal in and hold it, just enough to get the cable to lift the linkage off of it's stop. When the engine does fire, ( still holding the pedal in place, not pumping it, or letting it back onto it's stop )it stumbles around a bit, like the fuel in the lines had leaked into the cylinders ( black fuel smoke coming out of the exhaust pipe ), then, all of a sudden, r-r-r-UUMP! Foot off the pedal, and it will idle all day, start well all day, drive well, be a normal shark.

I'll certainly look at all those things mentioned before, but any other suggestions?

Sab

Greg,
where is that fuel damper and it's vacuum hose?
I am having some idle problems and a misterious fuel smell from time to time.
Could this be related?
regards,
Sab. <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />

Greg86andahalf

Sab,

On my car, the fuel dampner is on the rear of the engine, passenger side, below the air cleaner box. It has one small and one large vacuum line on it and fuel lines in and out. It is held to the block with a bracket.

Mine only leaked vacuum. No fuel leak or fuel smell. I'll need a few more days to be sure that the dampner was the problem. I keep disconnecting the battery to work on the car, so the computers are resetting. I'll try driving it for a few days and let things settle in. Then I should know for sure. i'll post result.

Greg

Greg86andahalf

UPDATE-

Dampner did not fix problem. I guess I got lucky after repairing it because it started fine cold. Once. I'm back to having to feather gas pedal to get car to cold start and hold cold idle for about 15 seconds.

Still hunting for the cause of this one.

Greg86andahalf

Update:

Replaced fuel pressure regulator and repaired a false air leak after using the innertube pressure method. (when presurizing, I had a fleeting vision of accidently over pressurizing and seeing all of the vacuum lines exploding off. It was only a fear, thank god!)

Car starts cold without using pedal. car also now idles 200 RPM higher than before. I should lower it, but I'm gonna wait and see if it balances out.

Thanks for all of the help.
Greg