Intermittent hesitation when pressing on accelerator

[kenchowder]

Not a car geek but am desperate for help.... I have a 1999 1.4 liter Berlingo that has been mostly great for ten years. For the past couple years I've had an INTERMITTENT fuel problem. Car starts up fine, idles perfectly. For about 500 yards or a kilometer it runs fine. Then AT TIMES BUT NOT ALWAYS, when I step on accelerator it coughs, hesitates. If I pull over and step hard on the gas it can backfire, and it smokes quite a bit (white smoke), and it looks like drops of liquid (gas or water) are coming out of the exhaust. The first time it happened the nearest car-repair place was several kilometers away. By the time I got there, it had stopped hesitating (the engine "coughs"); the guy couldn't find a problem. A year passed. Same thing happened next year. Again, wet conditions in late autumn. Car almost undriveable but managed to get to a repair shop; just as I pulled in, vroom vroom, it was running great again. Guy couldn't find anything wrong with it, put the engine through some tests, test-drove it, charged a lot of money and said I should get another car. It happened again, and I tried another repair shop. Same result: tests looked find. First guy said it couldn't be the fuel pump because it was intermittent. Second guy said it could be the fuel pump, but was likely the carburetor. He suggested I put some carburetor cleaner in the gas tank. I did and it ran fine for another year. Recently it's started to act up more regularly. A lot more regularly. What tends to happen is that it acts up, and I let it sit for at least an hour, and then USUALLY it's fine again. Also what can happen is that I can drive around for a while, limping, the engine coughing and cutting out (though not stalling), and then all of a sudden it's working fine again. When it starts to work okay, it always works fine the rest of the day, at least.

And now when I try using carburetor cleaner it certainly doesn't help.

So I took it to a fourth repair shop and he said he could only find out what was wrong if it was happening when I brought it in. He said it couldn't be the fuel filter (which I haven't changed in years). Not sure why not. Finally I manged to get it to the shop when it was malfunctioning. The guy pressed the gas, it coughed, he opened up the hood, and without further ado said the thought it was the "gas regulator," by which I guess he meant the fuel pressure regulator. Does that sound right to anyone here, or is he talking through his hat? How does he know it can't be a clogged fuel filter, or sediment or rust in the gas tank, or some other thing?

[Col]

Hasn't anyone in Denmark got diagnostic kit? You need to get it plugged in and come back here with the fault codes

[geoff]

Difficult to help from a distance but for me it would be prudent to use a new fuel filter prior to attempting any further works on the vehicle especially as it sounds like you will be paying a garage to do the work for you. If you can remove any possible influence that an old filter can have on the vehicle then any further diagnosis will be easier and not cloud the issue.

[Col]

Geoff, he seems to have this issue with cold wet weather, so I'm thinking something electrical, either ignition,wiring or a sensor acting up when wet which is why I asked for codes.
It seems he has taken it to less than competent people so far

[geoff]

Col my own thoughts were ignition related also but having read about his experiences at the garages so far I felt he ought to remove any red herrings before going any further, there appears to be plenty of scope here for being ripped off in a major way. For the work and cost of a fuel filter it is definitely worth doing to start from a known good position.

[polar]

Your mechanic could be right but i would put some good fuel cleaner in the tank first - Millers if you can get it then go from there.

backfiring can be down to a plug/HT leads breaking down or weak mixture.

[kenchowder]

Thank you all for your replies. The Diagnostic Kit is what all of the garages used but the car was working well when I got it to them, so no Error Codes showed up. The only time a Diagnostic Kit WASN'T used was the one time I managed to get it to the garage (this past Friday) while the car was still malfunctioning.

Isn't the Carburetor Cleaner (that I put in the gas tank) the same as a fuel cleaner? If so that seemed to work but these past weeks I've used it twice with no luck.

I'm very glad to have your suggestion to change the fuel filter first. That's what I wanted to suggest but I know so little about cars that I didn't want to tell a mechanic what to do or think -- not good behavior.

I also saw this on the Net about how to tell if a Fuel Pressure Regulator has gone bad (before replacing it). Does this make sense to you guys?

"Gasoline Is in the Vacuum Hose

"If you are noticing any of the signs above, but aren't convinced that the cause is a bad fuel pressure regulator, there is something you can do to be sure one way or the other. Remove the vacuum hose that attaches to the fuel pressure regulator, making sure the engine isn't running. If gas is in the line, your fuel pressure regulator is bad. Also, if there is none in the line, but, when you turn the switch on, fuel drips out of the hose, it is bad."

Incidentally, I've already spent about $500 on this problem, even though nobody even claimed they'd fixed it.

Again, many thanks for your time and trouble! Big help!

[geoff]

"Gasoline Is in the Vacuum Hose ......

Remove the vacuum hose that attaches to the fuel pressure regulator.... If gas is in the line, your fuel pressure regulator is bad. Also, if there is none in the line, but, when you turn the switch on, fuel drips out of the hose, it is bad."

The above is for testing the diaphragm inside the regulator - if diaphragm has failed the fuel will leak into the vacuum hose .... Petrol won't normally be able to pass the diaphragm.

How it works .... http://www.howstuffinmycarworks.com/Fuel...lator.html

I don't think yours has failed but do the tests yourself to prove, cheap and easy.

[Gadgetman]

I occasionally have the same problem with my 1.4i, and also believe it's an issue with the electrics somewhere.
I've noticed it tends to happen when the coolant temperature is just below normal working temp.
Stone cold or up to temp and it's OK.
Adding a steep uphill at the 'right' time doesn't help the issue, either.

I have found that stopping and starting it again usually clears the problem.
I would have used the diagnostics on it, but I haven't been able to get the durn thing to connect in ages...

Where is the fuel pressure regulator mounted on your car?
It can be in the pump(only one fuel line connecting to the high-pressure rail above the injectors) or at one end of the rail(metallic lump at one end of the HP rail, and two fuel lines, oe of which ends up by the regulator)

[kenchowder]

Thanks, Gadgetman. The fuel pressure pump is at one end of the rail (two fuel lines).

What you describe sounds exactly like what is going wrong with mine. It pretty much doesn't happen in the summer. It seems to be on wet cool days in the autumn when it's cold but not freezing. Once it's completely warm, the problem ceases. It also seems to stop when I drive through the problem, so to speak. What is perhaps stranger is that the problem also seems to stop when I simply turn the engine off for an hour or so.

Perhaps you can forgive my ignorance if I ask why an electrical problem might be temperature related? I can understand why condensation might affect an electrical system, but why would the temperature of the coolant affect the electrical system?

That said, it was the first guess of this mechanic, the fourth one who has looked at it. But now he thinks it is the fuel pressure regulator, though he didn't use a Diagnostic Kit to check. Guess he was too busy. Too bad, because this was the first time in five trips to a garage when the problem was actually HAPPENING when I got it there.

Thanks for your help! I'm grateful for the help of all of you.