Hello to all,

Been trying to trace down a hard start problem for a while now.
I noticed recently that the first cold start is immediate, no problem.
Then after a drive the engine warms up and I park it to go into a store.
Try an start the car now and it's crank-crank-crank.........
Only If I step on the gas pedal will it catch and start up.
It almost wants to die and then it smooths out idling fine like nothing ever happened?

Are we looking at some kind of vapor lock in the fuel system here?
Also my MPG has recently nose dived from 20-22 to 16.
That was after I set the distributor, replaced the plugs, wires, cap and rotor.

Thoughts?
Greg-

 

1990 Volvo 745? Check out the fault codes then
!

 

'set the distributor' ?

the timing on an lh2.4 car, including a 1990 turbo, is completely electronic. on a lh2.2 (NA up to 88, turbo til 89), the distributor sets the timing.

 

No fault codes at this time, I checked before posting.

"by set the distributor" I meant replaced the seals and Before reassembling the rotor and cap I made sure the
distributor was set in the correct place @ TDC.

 

gotcha. hmmm. 2.4 uses engine temp to know how rich to start... pull the ecu, and measure the resistance of the temp sensor, do it when the car is hot, and again in a few hours when cold.... I would to have to look up the pin and values.

 

first, *IS* this 1990 740 Turbo LH 2.4, or is it LH 2.2 ? 89 non-turbos were 2.4, and I *think* 1990 turbos were too, but maybe it was 91 ?

I only have the wiring diagrams for a 1991, but that should be the same if your car is also LH 2.4...

the engine coolant temperature sensor, ECT, has two pins, one goes to the ECU pin 13, and the other goes to ICU pin 2. so if you unplug the ECU or ICU, you can get to these circuits via the pins on the ECU/ICU socket...

if you put a multimeter set for "Ohms" (resistance) between one of those pins and ground (ECU pin 5, or ICU pin 14), you should measure a resistance proportional to the temperature...

• 32F (0C)-- about 6000 ohms
• 68F(20C) -- about 2300 ohms
• 104F(40C) -- about 1300 ohms
• 140F(60C) -- about 600 ohms
• 176F(80C) -- about 300 ohms
• 212F -- about 190 ohms

anything +/- 10% of these readings is fine. I would do this when the engine is hot, then wait a few hours and check it again with it relatively cold.

the ECU should be on the fender side of the passenger footwell, just forward of the lower passenger door hinge.

 

Change your Fuel Pressure Regulator! Most likely cause of the symptoms you describe!

 

This is a 1990 745 turbo.
Ashamed to say not sure if it's 2.0L or 2.3L?
I'm all for throwing parts at it!

 

a US model turbo would be a B230FT. the 2.2 vs 2.4 stuff I'm talking about is the fuel injection version, LH2.2 was used on older versions, LH2.4 is used on later ones. the switchover years were 89 for non-turbo and 90 or 91 for turbo.

 

Well it's not a Regina system if that helps?
How can I tell which is which?
Is it in the vin #?
I could always upload a pic too.

 

ALL TURBOS have Bosch ignition! Change your FPR!

 

turbos are never regina, always Bosch.

Um, LH2.4 systems have a onboard diagnostic box near the left suspension tower, behind the power steering pump. this is a little black rectangular box with a lid that lifts up, under the lid are 8 holes labeled 1-8, a LED, and a pushbutton, and there's a little jumper wire. Thats the most obvious change.

LH2.4 cars use a crank position sensor for their main timing, this is on the back of the engine block just below the head, that reads pulses off the flywheel. LH2.2 cars use a hall effect sensor in the distributor for timing....

LH 2.4 cars have a -016 MAF/AMM (mass air flow sensor, aka air mass meter, -016 is the last three digits of the Bosch part number on them), while LH2.2 cars have a -007.

otherwise they are pretty similar. the brain inside the ECU is more powerful on the 2.4 system, but both are damn primitive compared with anything modern.

 

You had me at diagnostic box..............

It's a LH 2.4!

Changing the FPR this week lev, thanks.
I'll let you know if it worked by Saturday.

 

If the dipstick smells strongly of fuel or there is a strong smell of fuel on the vac hose of the fpr, the internal diaphragm has failed. Still, if the car runs fine and there are no codes, my $$$ is on the ect. Let us know...

 

I think it was the FPR.
Replaced it Tuesday and there is a noticeable dIfference in the way the car starts. Now I turn the key and in one or two cranks its running. I'm also curious how this will effect the milage. Thanks all for your great suggestions. After a couple of days driving we can call this problem solved.
Greg-