Randolph

I'm under the impression it can NOT be adjusted on an 87 5KCSTQ.

Reading through SJM mentions that on an 89-90 MC-2 they use an external canister type fuel pressure regulator that can be adjusted but the 86-88 MC-1 has an internal fuel pressure regulator that can be repaired or replaced. Do I have this correct?

Now that the warmer weather is coming I'd like to address this issue of my vapor lock symptoms that I always have. SJM mentions very similiar symptoms that my car suffers BUT he talks about these symptoms on a 89-90 200 with the external regulator. He says how he found that the fuel pressure was actually going UP after sitting for a while due to heat soak. Only difference I have from what he described is my car starts right away but will run like it's flooded for about a half min till it clears out. New injectors did not alleviate this problem. I have not put fuel guages on the car to check this. I don't even own fuel pressure guages so I'm wondering if I should just attack this said fuel pressure regulator? Or if someone wants to point me in the right direction....

R

audi_marv

Yes, you can adjust the fuel pressure on an internal regulator. The regulator is located on the front of the fuel dizzy by a 13mm(?)nut that holds the needle, spring, o-rings, and shims. If you add shims, this will increase the fuel pressure. A shim will raise the pressure 1-3 psi, depending on the shim thickness.

Your internal fpr may have 2 or 3 o-rings at each end, and they may be old, or missing. This may be causing your hot start problem. Autohaus has the whole fpr kit this for about 40 bucks.

Usually the problem is with the fuel accumulator, but if you have ruled this out, then the primary fpr is the next place to go. When re-installing the piston, apply a thin coat of oil around it so it slides easier.

Here's a photo of it...

a-talk

So you've got this regulator (either internal or external depending on MC1 or 2), and you've also got the control pressure regulator. Which one dictates the true control pressure at the injectors?

Randolph

[QUOTE=audi_marv;23943634]Yes, you can adjust the fuel pressure on an internal regulator. The regulator is located on the front of the fuel dizzy by a 13mm(?)nut that holds the needle, spring, o-rings, and shims. If you add shims, this will increase the fuel pressure. A shim will raise the pressure 1-3 psi, depending on the shim thickness.

Your internal fpr may have 2 or 3 o-rings at each end, and they may be old, or missing. This may be causing your hot start problem. Autohaus has the whole fpr kit this for about 40 bucks.

Usually the problem is with the fuel accumulator, but if you have ruled this out, then the primary fpr is the next place to go. When re-installing the piston, apply a thin coat of oil around it so it slides easier.

Here's a photo of it...

Awsome, Thanks! That helps me see what I'm dealing with. I'm gonna save that image for reference. The fuel accumulator was replaced a few years ago but the car did this even before that was changed. Fuel pump was also replaced. I may go ahead and get some fuel guages so I can check the pressure readings and make sure but I'm fairly confident that those o-rings you point out are my problem.

R

audi_marv

I would say its the int. or ext. FPR that influences the fuel pressure at the injectors. After shutoff, the FPR reduces pressure to a point where there's no fire hazard, but only to where the pressure can still quickly open the injectors on re-start.

When you have the hot start problem/vapor lock, the pressure dips too low, that is, too much gas is going out of the lines back to the tank, and air gets in the lines until constantly cranking the engine builds the pressure back up (can also have leaky injectors-or both to cause this).

You mention the control pressure regulator, which i think you are referring to the WUR warm/cold control pressures. This affects the pressure in the fuel dizzy, and rich vs. lean at start up. Contrary
to popular belief...the WUR pressure can be adjusted also.

Randolph

If I'm reading you correctly, your saying that a hot start/vapor lock problem is cause of the fuel pressure dipping to LOW? I thought it was because it was too HIGH. Just to be clear, I do not get extended cranking. Starts up BUT wants to run like its flooded for about 30 secs or so and it is very realated to outside temperature. The warmer it is out the worse, the colder out the less it does this.

I looked at the FPR on the front of my fuel dist like you pointed out. I'm wondering if should remove it and inspect? I'm hesitant to touch it without any of the new O-rings on standby. It doesn't look like it's ever been touched.

Also, looking at my fuel dist, should it be somewhat wet looking and dirty where to top part of it meets the bottom of it. I don't smell any fuel at all but it looks a bit wet with grime stuck to it. This is in the area where there is a metal tag with a number on it.

Thanks much for walking me through all this as I've never dealt with this kind of problem before but I really want to get it handled.

R

audi_marv

Got the dreaded "broken radiator coolant hose connector", so i'll have to f/u with you later.

Can you explain more about the "runs like its flooded"?
Hot Start is a can of worms. Could be your injector fan is not turning on, and your fuel i bubbling in your lines.

More later....time to go get durty .

Randolph

Ah, the ol hose connector problem. Luckily the prior owner replaced the radiator before I bought the car so I haven't had to deal with that. I did replace that hose and was very careful removing it from that nipple.

What I mean by "runs like it's flooded" is when I go to start the car when the engine is already warm from being driven earlier it will start up fine then immediately go into a low idle and almost "lope" like the car has a cam in it then it clears up and smooths out after 30secs or so. No visible smoke or fuel smell noted out of exhaust. If I keep my foot on the gas pedal just a bit I can avoid this whole ordeal and it clears up a bit quicker. Car is usually fine on the first start of the day, it's later after the engine is already warmed up and the car has to be restarted.

For example, I drive car to the store and go shopping for an hour. When I go to restart the car it will want to do what I described above. The warmer it is outside the more noticable this is, the colder it is out the less noticable it is but it does tend to always do it.

Here's a list of what's been done to the car that could cause this problem but has not had any effect on alleviating this problem
New injectors, seals, inserts, 02 sensor (approx 1.5 yrs ago)
New fuel pump & ck valve (approx 5 yrs ago)
New fuel filter (2 mos ago)
New fuel accumulator (thing in rear of car by pass tire)(approx 4 yrs ago)
plugs, wires, cap rotor (this past winter)
various sensors (when injector job was done)
no vacuum leaks
ISV replaced (approx 5 yrs ago) (have re-cleaned current isv once)
car shows no codes
Injector fan has been tested & does work and I'v heard it kick in on it's own. (SJM mentions a lower temp sensor from the 200's is avail for this but mine is the original I believe)

I have zero drivability problems with the car. It purrs like a cat and pulls strong and smooth. Even being a 5cyl you have to look at the tach to even know it's running when at a stop light.

Also note the car has always done this even BEFORE all the above mentioned parts were changed. The only thing I haven't looked into is fuel pressure or anything having to do with the fuel distrib or the WUR.

Thx again and no hurries on getting back to this post. This is not an emergency.

R

audi_marv

Sounds like your Cold Start Valve is the culprit. When the engine is cold you need the extra gas, but when things warm up, sounds like its staying open, and you're getting too much gas at start up. It fires extra fuel for up to 10 seconds, shuts off....and then your car smooths out.

You said it yourself, that its "Temp Related", so I would focus on the Temp Sensors and the CSV. I think the temp sensor involved is the one in front of spark plug #1, under the PS Pump bracket. They only cost about 8 bucks.

Your ISV may be borderline, as 5yrs is about right for an aftermarket one.

My problem is just the opposite. I'll shop for an hour, come out...and its Crank, Crank, Crank,....until the fuel pressure pushes the air out of the
injector lines, and the car starts. This is what i think of as a "hot start" problem. Think I was sold a bad Pressure Accumulator 2 yrs ago.

BTW....had to bite the bullet on a new Modine radiator.
Who was the moron that came up with the idea of plastic side tanks
on a high temp turbo car !!!

Randolph

Yeah, I don't know of anyway to really fix that nipple except to get a new radiator. Not the best design at all.

I forgot to mention that my CSV was also replaced when I did the injector job. The old CSV was suspected to be bad and after running the output tests was confirmed. I think last summer I experimented and unplugged the CSV before restarting the car and it didn't make any difference but maybe I should try it again to verify. I'll look into those sensors more. They are both new (when injector job was done) but maybe the wiring is suspect. Thanks again for the suggestions. I'll update when I eventually get it fixed. I'll probably order some CIS FP guages as suggested by a-talk (on other forum) so I can at least ck the FP and see what I'm dealing with.

R