Today's troubles, loss of power

[Gfrank]

Hi all, had talked about this problem last summer and thought it to be concured. How ever yesterday on my drive home it showed up again.
About half way through my 45min drive home (about 55mph all the way) as I am coasting down a long steady hill in gear it almost bucks a bit if you will, clutch in ,seems to idle back no problem and no bucking. Come to a stop at a few lights before my subdivsion, start to ease into the throttle keeping it steady, it's almost as if it's got no power then all at once she takes off as if I have nitrous lol same result at the next few lights. Well waiting for them to go green she seems to idle normal area however Id say slightly rougher. Haven't driven it again, but once I was into the subdivsion she seemed fine again, hammered on it down my street and it seemed normal.
I've got some ideas but more or less grasping at staws. I'm assuming it's fuel troubles, suggestion?

Bit of back ground, last year I cleaned the tank inside vary well, new pick up filter, aswell installed a spring into the pick up line to pervent collapse. New boot and cover.
Plugs cap wire rotors fuel filter done last spring

Thanks in advance for any help!

[DMCMW Dave]

I've seen a sticky fuel distributor or sticky air flap mechanism do that. It needs to be essentially frictionless, and if it isn't the car will be wildly lean for a few seconds as you accelerate, and then clear up. It will be very rich if it sticks on the way down, but you don't usually notice that as much unless you get fire out the tail pipe.

Also make sure there are no restrictions/kinks in the fuel return line, that will really upset the fuel pressures in the system and make it run strangely as well. Look for kinks in the hose that goes to the return line on the pump, about the only place it can happen since everything else is hard line.

[David T]

[QUOTE=DMCMW Dave;171984]I've seen a sticky fuel distributor or sticky air flap mechanism do that. It needs to be essentially frictionless, and if it isn't the car will be wildly lean for a few seconds as you accelerate, and then clear up. It will be very rich if it sticks on the way down, but you don't usually notice that as much unless you get fire out the tail pipe.

Also make sure there are no restrictions/kinks in the fuel return line, that will really upset the fuel pressures in the system and make it run strangely as well. Look for kinks in the hose that goes to the return line on the pump, about the only place it can happen since everything else is hard line.[/QUOTE/]

Another thing to check is the frequency valve. If it stops the engine will lean out and lose power. Take the plug off the valve and put it back on a couple of times to clean up the contacts.

[hmcelraft]

Sounds sort of like a frequency valve when one isn't working consistently. Electrical connections at the valve ok? How old is your RPM relay? Many OEM units had dual points - one for the fuel pump and one to run the lambda and frequency valve. I've had the lambda one not work intermittently on more than one of those RPM relays and causes a symptom like you describe. Intermittent at first then more frequently. Replacing the RPM relay fixed it.

[Gfrank]

Thanks for the sysgestion's guys! forgot to mention the front rubber lines I replaced last year aswell and I laid them out real nice. All should be good up front, one thing that has been sygested I do and i haven't yet is replace the stock fuel pump connection. I have cleaned it, but still stock.
Going to try to make time this weekend to check out the plungers and connections, in a pinch I can steal the frequency valve off my 82 to try. Relay system was replaced by the owner before me, believe they have dmc2013 on them. I shall check connections on it aswell.
Anyway to test the frequency valve?

Btw Dave s, didn't want to bother you with a call, but got your message and thanks so much for getting me that brake line on the way for my 82, much appicated!!

[Gfrank]

Other thing to add possibly related, a problem I have always had with this car is bit of a rough start after sitting over night or for several hours (has no problem starting, but runs rough) Clears itself out after only a few seconds if you give it a bit of gas. I generally will turn the key to run twice to prime before I try to start, always assumed I have a leaking down injector

[Gfrank]

I lied, rpm relay is an original unit. I do have another spare original In the car
I didn't get into unplugging things as its dark out, but fired the car up, frequency valce seemed to buzz away like normal, wiggled some wires with no change

[David T]

I lied, rpm relay is an original unit. I do have another spare original In the car
I didn't get into unplugging things as its dark out, but fired the car up, frequency valce seemed to buzz away like normal, wiggled some wires with no change

Don't just wiggle it, actually pull the plug off the valve and put it back on a couple of times. It may be working now but it could be intermittent and when it is not working the mixture will be too lean.

[kings1527]

Quite honestly, I wouldn't mess around with OEM RPM relay anymore. You may want to get in touch with Dave McKeen (bitsyncmaster) and look into getting one of his solid state RPM relay rebuilds and never have to worry about it again.

[Gfrank]

Don't just wiggle it, actually pull the plug off the valve and put it back on a couple of times. It may be working now but it could be intermittent and when it is not working the mixture will be too lean.

Perfect thanks Dave, will do, just wasn't getting into it the other night, I did have a few min to tinker this evening, air flap seems to move smooth no problems, I also pulled the injectors out and did a cup test, all seem to spray about the same, how ever have two or three with bad atomization, more just a stream. Look into having them clean first. I am loosing fuel pressure at the distributer over night

I was thinking I may just grab an updated rpm relay regardless, one less thing to think about

[David T]

Perfect thanks Dave, will do, just wasn't getting into it the other night, I did have a few min to tinker this evening, air flap seems to move smooth no problems, I also pulled the injectors out and did a cup test, all seem to spray about the same, how ever have two or three with bad atomization, more just a stream. Look into having them clean first. I am loosing fuel pressure at the distributer over night

I was thinking I may just grab an updated rpm relay regardless, one less thing to think about

Right now there is no reason to think the RPM relay is bad. When diagnosing the less you disturb the better so you can find the problem. If you mess with everything and the problem goes away you will never know what actually did it. Dirty injectors would not cause a problem that comes and goes. Try a can of Techron.

[Elvis]

I was thinking I may just grab an updated rpm relay regardless, one less thing to think about

it's so simple to check and fix them - go for it.

[Gfrank]

Well up date, did some tinkering, check the sysgestions and nadda.
Took the car around the block sat to get some ice cream with the wifey. Idled fine and drove dandy on the 3min drive there. On the way back (took the long way around the block) she started back into the bucking and pulsing. Was listing to it once back in the drive way (seemed to idle fine at that point) but if I gave it a quick rev and let off I was getting a small pop/back fire more or less everytime

[David T]

Well up date, did some tinkering, check the sysgestions and nadda.
Took the car around the block sat to get some ice cream with the wifey. Idled fine and drove dandy on the 3min drive there. On the way back (took the long way around the block) she started back into the bucking and pulsing. Was listing to it once back in the drive way (seemed to idle fine at that point) but if I gave it a quick rev and let off I was getting a small pop/back fire more or less everytime

Does it get any better once it is fully warmed up and the cooling fans have cycled?

[Gfrank]

Can't confirm Dave if the problem exists when the car is cold as generally by the time I'm out of the subdivsion the car has some heat in, but from what I can tell the problems not affected by heat.