1. Home
  2. Volvo automobiles
  3. S40 hard starting, uneven running

S40 hard starting, uneven running

Hi all,

I'm hoping to get some direction as to what and where to test with the purpose of getting to a diagnosis on a problem with my 2001 S40 1.9T (auto with about 240K).

Since I've had this car it's been quite reliable and has had few problems (except the recently fixed turn-signal issue). About a month ago it began getting a little harder to start. The starter motor would turn but the engine wouldn't catch for a few seconds. Over the past several weeks this time before starting has been getting longer.

A few observations:

  1. The hard starting happens always when the engine is cold and about
50% of the time when it's hot.
  1. When it cranks for a long time (5 seconds) before catching there's a strong smell of gasoline
  2. The starter motor cranks hard and steady, there's no sign of weak battery.
  3. It has not yet failed to start or stalled out while running.
  4. Once it starts it doesn't idle smoothly insofar as it seems to 'miss' every now and again and give a little shudder. No noise, just a very short gap in the otherwise even idle.

What I've done to make it worse :) A couple of weeks ago I had a driveway to work in so I picked up some spark plugs thinking they might be the problem. Unfortunately I couldn't find a gapping tool OR the appropriate gap specifications for this car so I just swapped them anyway because the old plugs were in pretty bad shape (the plastic around the annode was almost entirely worn away and blackened). Since that time the idle has worsened and there have been more misses at highway speed. I suppose that when I address this (does anyone have the right spark gap measurement for this car? I can't find it in VADIS) I'll need to use new plugs again.

A few more observations:

  1. The tach shows idling RPMs a bit low, looks like approx. 600rpm.
  2. The 4 spark plugs are fed by two ordinary wires and two that have a sealed box just above the plug socket. In researching them on VADIS I found that the springs inside the sockets were supposed to protrude
5mm when disconnected from the spark plug but these did not:they were compressed to even with or lower than the socket edge.

So if that information makes the problem obvious to anyone then that's great but more likely you might have suggestions on what to test or inspect to work towards a conclusion.

Whatever you've got I'll take with thanks!

Cheers, blurp

Reply to
blurp
Loading thread data ...

My '01 S40 (150K miles) had a similar problem - turns out it was the fuel regulator.

Reply to
Lloyd W.

From what you are describing it sounds like the fuel pressure regulator is on it's way out not very hard to change remove the fuel line going in to the regulator remove the torx screw from the side of the fuel rail very slowly work out the regulator install is opposite of removal Glenn K Volvo Certified Technician 2008 ASE Certified Technician 2008

Reply to
GlennK

My 2000 S40, which now has just over 200,000 miles on it, has similar problems. I have pretty much ignored the hard starting and it has not gotten any more serious in the two plus years that has been an issue. As far as the rough idle/missing, I've used a can of Seafoam about once a month and that seems to clear things up pretty well. Despite the troubles described, this car has been a trooper for me since I got it new in Nov. of

1999. Maybe I'll give the fuel pressure regulator a shot and see if I can get a few more years out of her. The suspension and body are starting to show their age though.
Reply to
Steve and Amy Bernth

Thanks for the responses I've received, it's good to have something specific to start chasing down.

So is there any way I could test the Fuel Pressure Regulator without removing it or am I just replacing it?

Reply to
blurp

UPDATE

I went to inspect the fuel pressure regulator and found that the short length of U-shaped hose that connected the regulator to the engine (the black part AFTER the short length of cream-coloured hose) had cracks in it. So if it's leaking at those cracks is it leaking fuel out or leaking air in? The hose seemed dry and dusty so I don't think anything has come out of those cracks.

The dealer says they sell the double-ended S-shaped hose assembly for $14 so I think that's what I'll go pick up today after work. Any procedural suggestions re: swapping that out? Is there going to be residual pressure in the fuel system when I take the thing off? Can I alleviate that by opening the fuel tank? Will I need to bleed the fuel system afterwards for fear of air bubbles or will it correct itself?

I don't have any experience working with the fuel system and want to be as safe as possible.

Thanks, blurp

Reply to
blurp

ANOTHER UPDATE (bottom):

I found this beautiful step-by-step for other users:

formatting link
929&rid=&S9228a07c49c92cfd8e3d8b35c4d02d3 and I believe the part I'm seeing the cracks in is a vacuum hose so I'm increasingly thinking no fuel is likely to come out as a result of this repair.

Hopefully I can change this hose without having to completely remove the FPR.

Any advice/suggestions still welcome!

Thanks, blurp

Reply to
blurp

formatting link
929&rid=&S9228a07c49c92cfd8e3d8b35c4d02d3>

The hose is a vacuum line that allows the regulator to maintain a constant pressure across the injectors as the pressure in the manifold changes. No fuel will come out if it leaks, but the fuel pressure will not be correct under many circumstances, as well as it creates a vacuum leak into the intake manifold which will cause the engine to run poorly.

Reply to
James Sweet

formatting link
929&rid=&S9228a07c49c92cfd8e3d8b35c4d02d3>>

That sounds promising, I picked up the replacement hose this evening and hope to swap it tomorrow. It'd be nice to solve this with a $14 part. So the stuff in my previous post about gapping the plugs... can I rely on them being correct right out of the box? What if i had got the plug with 4 grounds?

b
Reply to
blurp

Generally no, you can get pregapped plugs, but it's always a good idea to check them, a gapping tool is usually under a dollar.

Those multi-electrode plugs are a gimmick, just get plain plugs of the correct heat range, I've had good luck with NGK. If you pay more than $3 each, you got ripped off.

Reply to
James Sweet

That's what I was afraid of... I'm going to have to pull those plugs again once I geet a gapping tool. Just got the correct gap a few minutes ago: 0.70 to 0.80mm. I got the Bosch Platinum with one ground.

Cheers, b

Reply to
blurp

Swapped out the little vacuum hose to the regulator and all appears to be well.

Thanks a bunch! blurp

Reply to
blurp

Ooops, spoke too soon! It was better for a day and now it's back to as it was. Perhaps I jarred the regulator when installing he vacuum hose and it worked for a day and hen went back to failing.

sigh. next I guess I try a new regulator ($300).

blurp

Reply to
blurp

This seems to be a job that never ends! New Thread to follow.

blurp

Reply to
blurp

Anyone fitted them to a 2001 S80?

Reply to
Uncle Albert

What sort of LED lights? Interior lights? Marker lights? Brake lights? Headlights? Fog lights?

Reply to
James Sweet

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.