240DL 1990, Very hard to start when warm/hot, without Gas pe

sam11 · Post by **sam11** » 26 Oct 2008, 10:34

Hi everyone. MY Car will start very well when cold, but after warm up or after driving for a while, it becomes very hard to start without stepping on the gas pedal. The result of this is the smell of unburnt gas, and a noisy belt while starting, i think its either the Timing belt or the starter motor belt. I did a complete tune up; changed spark plugs/cables, rotor, fuel filter, air filter, airbox temperature sensor, oxgen sensor, airmass flow, coolant temperature sensor, recently changed Timing belt too. Haynes Manual not working very well with me this time. Help!

Post by **billofdurham** » 26 Oct 2008, 12:58

Welcome to Matthew's Volvo Site.

i think its either the Timing belt or the starter motor belt

There is no starter motor belt.

It seems like you have replaced quite a lot of items and if this has only appeared since they were replaced the first step is to check everything to make sure that wires, especially ignition and sensors are properly connected.

Which coolant temp sensor did you replace? There are two, one for the gauge (usually called a sender) and one for the ECU.

Your car is fitted with an On-Board Diagnostic unit in the engine compartment which would show if any fault codes have been stored. Instructions on its use are at: https://www.matthewsvolvosite.com/forums ... c&start=12.

Bill.

sam11 · Post by **sam11** » 26 Oct 2008, 18:02

Thanks for your thoughts. I was having this problem before i did any work on this car. First i thought it was the airmass meter. But this did not solve my problem. Haynes manuals keeps referring me to the cold start valve and the thermo-time switch. The cold start valve and the Thermo-time switch are kind of expensive to replace and i wanted to get some insight before i touched them.

J_Westy · Post by **J_Westy** » 26 Oct 2008, 19:08

sam11 wrote:Hi everyone. MY Car will start very well when cold, but after warm up or after driving for a while, it becomes very hard to start without stepping on the gas pedal.

I'm chasing the same thing on my '92.

I didn't have a maintenance history, so like you, I did a tune-up. Air filter, plugs & wires, cap & rotor, wiped out throttle body with carb cleaner.

I also mistakenly replaced the TPS because the Bentley was wrong.

The next thing is the crank speed sensor. Forum wisdom is that this sensor is a near maintenance item

Working theory is the sensor is weak when hot and doesn't start reading speed until a higher then normal speed.

My sensor should be here tomorrow...

J_Westy · Post by **J_Westy** » 29 Oct 2008, 19:03

J_Westy wrote:My sensor should be here tomorrow...

The crank sensor didn't work, but it was cracked so it was good to replace proactively.

Next up is the fuel pressure regulator.

I'm tracking my progress here: http://forums.turbobricks.com/showthread.php?t=150548

sam11 · Post by **sam11** » 30 Oct 2008, 19:25

I have been looking at afew other things here. First in the Haynes manual i came across the other valve that i never thought of before. The WARM start valve found only on certain Volvos. Haynes manual Chapter 4 section 11. If your car doesn't have this then you have the EVAP. connected to the Engine at the throtle body area, by a vacuum hose and a bigger fuel hose. These lead to the Evaporative emission control (EVAP), which store fuel vapors generated in the fuel tank in a charcoal canister. Located at the left front end of your car. Anyway you can find more infor. in the haynes manual in CHAPTER 6, section 9. Well check it out just incase. I will check mine probably this weekend. I want to check out this crank position sensor too, where it located?

J_Westy wrote:
J_Westy wrote:My sensor should be here tomorrow...
The crank sensor didn't work, but it was cracked so it was good to replace proactively.

Next up is the fuel pressure regulator.

I'm tracking my progress here: http://forums.turbobricks.com/showthread.php?t=150548

J_Westy · Post by **J_Westy** » 30 Oct 2008, 21:19

sam11 wrote:Well check it out just incase. I will check mine probably this weekend. I want to check out this crank position sensor too, where it located?

I'm 99% sure a new fuel pressure regulator fixed mine. See my saga here (first post is the chronological summary): http://forums.turbobricks.com/showthread.php?t=150548

The crank sensor is on top of the transmission bell housing. Maybe I was looking in the wrong place in the Bentley and Haynes, but I could not find info on the sensor there. Anyway, there's a 10 mm bolt holding it on. You can reach it from up top with 15" of extensions and a universal joint. It plugs in just behind the valve cover on the fire wall.

Here's some links that may help:
http://www.brickboard.com/FAQ/700-900/E ... ion_Sensor
http://forums.turbobricks.com/showthread.php?t=144533
http://forums.turbobricks.com/showthread.php?t=98459

wojeepster · Post by **wojeepster** » 31 Oct 2008, 08:02

A second vote for faulty fuel pressure regulator. Pull vacuum line off and see if there is gas dripping out of it. If so the diaphram has a hole in it. I was having the same problem. I found one for $76 at www.fcpgroton.com

J_Westy · Post by **J_Westy** » 31 Oct 2008, 12:40

wojeepster wrote:A second vote for faulty fuel pressure regulator. Pull vacuum line off and see if there is gas dripping out of it. If so the diaphram has a hole in it. I was having the same problem. I found one for $76 at http://www.fcpgroton.com

In retrospect, I wish I would have done that check. I did have fuel dripping out of the vacuum port when I took mine off though.

Thumbs up for partsgeek.com -- I've gotten my parts next day with regular shipping and prices are very good. My regulator was $60 including shipping.

russellhatcher · Post by **russellhatcher** » 20 Aug 2016, 14:32

Have you checked thermostat? Mine was broken and computer was treating engine as cold. It was giving to much fuel to engine.