3.6 conversion slow to start

johnsjmc · 08-08-2005, 06:05 PM

I have my 1990 3.6 installed and running in a 1980SC but a few questions.1) It seems to crank too long before starting. Is there anything holding pressure in the fuel rail or does the system rely on the pump immediately pressurizing the injectors when the position sensor detects rotation?
2) Idle oil pressure is 1.5 to 2 bar but pressure peaks at 3.5 bar at about 3500 RPM hot , no higher when reved .Oil is fresh mix of 20w50 Dino and 15w50 synthetic. Is there a compatability issue with the 3.6 sender and the 1980 guage? I haven,t checked with a mechanical guage yet.
3) Where is the O2 sensor plug ? Is it the round 3 pin on the driver,s side near the plug bracket and coil feeds?

einreb · 08-08-2005, 06:54 PM

Quote:

Originally posted by johnsjmc
1) It seems to crank too long before starting. Is there anything holding pressure in the fuel rail or does the system rely on the pump immediately pressurizing the injectors when the position sensor detects rotation?

John,

I'm no help other than to say that my 3.6 conversion does the same thing. You got me thinking... if you turn the key to 'on' for a few seconds (activating the fuel pump?) and then crank... does it start right up then? Mine's on stands at the moment. I'll do that when it hits the ground.

Hopefully someone brighter than me chimes in on this.

-bernie

johnsjmc · 08-08-2005, 07:04 PM

The second stage of the DME relay turns on the pump when the crank sensor detects rotation. The pump doesn,t run otherwise. I want to know if there is any one way setup that would hold line pressure like the pressure accumulator in the CIS system?

einreb · 08-08-2005, 07:09 PM

Quote:

Originally posted by johnsjmc
The second stage of the DME relay turns on the pump when the crank sensor detects rotation. The pump doesn,t run otherwise. I want to know if there is any one way setup that would hold line pressure like the pressure accumulator in the CIS system?

Obviously, your already way ahead of me...

Wayne 962 · Wayne 962's Garage

Quote:

Originally posted by johnsjmc
The second stage of the DME relay turns on the pump when the crank sensor detects rotation. The pump doesn,t run otherwise. I want to know if there is any one way setup that would hold line pressure like the pressure accumulator in the CIS system?

I'm thinking something else is wrong. Pressure should be almost instantaneous (like any modern car). Have you checked the fuel pressures in the rail?

-Wayne

Bill Verburg · Bill Verburg's Garage

They should start instantly.

SalazarS2K · 08-08-2005, 07:28 PM

My car does the same thing and I haven't been able to find out why the car doesn't start up right away. (I have a late '91 3.6L) The fuel does not seem to hold any line pressure. The only time it starts up right away is when I drive it the day or two before I start the car again; any longer than a week and the car is real slow to fire up.

einreb · 08-09-2005, 05:22 AM

bump for the morning crew...

Bill Verburg · Bill Verburg's Garage

I can leave mine all winter it still starts immediately(both setups that I have had). Have you guys got the fuel accumulator hooked up? Pressure regulator and vacuum valve?

johnsjmc · 08-09-2005, 05:42 AM

I removed the 3.0 with it,s accumulator ,filter etc. I ran a new steel fuel line from the tunnel to a new filter location on the right side ahead of the oil tank then into the right side rail. The return is from the left side back into the SC steel line . The stock 3.6 pressure reg is there . What vacuum valve do you have in mind?

Bill Verburg · Bill Verburg's Garage

'90 964 fuel

vacuum control is #24, pressure regulator is #17

johnsjmc · 08-09-2005, 02:12 PM

Both are there What is the function of #24? The regulator may be bleeding away pressure when stopped. I will try pinching the return hose and dig out my system pressure guage and see if I have a fitting which will fit the fuel rail. That may tell the storey better.

blue82coupe · 08-09-2005, 02:31 PM

Bill, are using the cis fuel pump and did you retain the accumlator? My car does the same thing.I removed the accumulator and used the hi pressure cis pump. My engine is from a 95 993. Could it be that the regulator is bleeding pressure between starts because of the 100psi or so pump? Dan

rattlsnak · rattlsnak's Garage

Mine does the same thing. I also have no Accumlator. One of these days Ill put one in. I just ran the fuel line right from the pump directly to the fuel rail. Once I start it, it will be fine for the rest of the day. But the longer it sits, the longer it takes to prime. Usually no more than 15~20 seconds of cranking though.

david.avery · david.avery's Garage

Are you using the tired starter from 1980?

Years ago I had to go with a High Torque starter for mine to fire properly.

Bill Verburg · Bill Verburg's Garage

You do not want an accumulator, mine has the cis pump, I vaguely remember that some cis pumps may have had a check valve on them. Have to do some research on that.

tholyoak · 08-10-2005, 06:33 AM

According to the factory manual the following could result in a hard to start car

Idle speed contact short to ground or break
Engine temp sensor II
Idle speed control activation
Faulty DME
DME relay
Tank venting valve
Injection Valve
Fuel pressure
Intake leak
ground and plug connections
speed/ref sensor
ignition system and output stage.

You need to hook up the fuel pressure gauge and see how long you maintain residual fuel pressure. The factory spec is after shutting down the motor the residual pressure should be 3.8 bar, and the max drop in 30 min should be 0.5 bar. As Bill said with the CIS pump there is a check valve in the pump output that can be the culprit if the pressure is not remaining after shutdown.

Todd

einreb · 08-10-2005, 08:42 AM

Todd, thanks for the list ... thats a lot of good stuff to check.

I also just got an email back from timmons. His first suggestion was the fuel check valve. quite frankly, I don't know if my '88 even has a check valve... but I'll look into it.

Jack Olsen · 08-10-2005, 09:47 AM

As a data point, my 1993 motor starts right up no matter how long it's been sitting. I have a 964 fuel pump and (although it shouldn't matter) a high-torque starter.

Mike Feinstein · Mike Feinstein's Garage

Quote:

Originally posted by rattlsnak
Mine does the same thing. I also have no Accumlator. One of these days Ill put one in. I just ran the fuel line right from the pump directly to the fuel rail. Once I start it, it will be fine for the rest of the day. But the longer it sits, the longer it takes to prime. Usually no more than 15~20 seconds of cranking though.

Mine does the exact same thing. Nature of the beast I guess.