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85 GT Losing Power While Driving by CZSeventyFive
Started on: 10-02-2020 12:54 AM
Replies: 17 (171 views)
Last post by: Patrick on 10-17-2020 05:06 PM
CZSeventyFive
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Report this Post10-02-2020 12:54 AM Click Here to See the Profile for CZSeventyFiveSend a Private Message to CZSeventyFiveEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi all, I signed up a little while ago but this is my first post. For most problems I've referred to other threads, but now I'm simply stumped.

I got an '85 GT, bought it back in May. Recently I've been having some major issues with it, namely that it will lose power while driving--the gas pedal for example won't give any power upon pressing it down all the way, although sometimes (but not always) upon release the car will jerk forward, and just tonight I found that I could just repeatedly stomp the gas to keep it moving with little bursts, although I doubt that's good for it.

When I first got it it seemed to run rather well, albeit with a high idle at times. As time went on the idle got worse, which I figured was a vacuum leak occurring somewhere. The seller apparently believed that the fuel pressure regulator needed replacing and was causing irregular fuel consumption and possibly the high idle. I did notice that my fairly lengthy commute from home to any form of civilization was a long enough drive to make any fuel consumption noticeable on a single drive, and sure enough at first it seemed to eat fuel with abandon, although this leveled out over time and became much better. I'm not sure what that meant, although the car had sat for two years at least before I took it home.

Anyways, I spent a day driving it back and forth and it worked just fine. Then, on the next morning taking it to town to my dad's building, it suddenly began to lose power. At this point I had been in fourth gear going about 70 mph down a country road. I simply let off the gas at one point a third into the trip, and then when I pressed down again the car stuttered and rapidly lost power. It came to standstill and I put it in neutral and the car continued to run, although the gas pedal still failed to propel it. I turned it off, and then started it up again, and continued for another several miles as if nothing happened. But then it happened again, this time as I tried to move from third to fourth gear. This starting and stopping and restarting continued until I reached my destination. The car would remain here for a little while. As such, my first order of business I decided was to replace the FPR as the seller suggested. The first pulling apart of the engine led to two beheaded screws, one of which was one holding down the FPR itself (the other one on the upper manifold itself, although it was one that seemed to just hold a strap down and wasn't one of the main ten). Despite our best efforts, these had to be drilled out and the holes retapped. I replaced some gaskets for the vacuum leaks, and then like an utter fool I placed the ring that held down the FPR cap underneath the cap instead of on top of it. This was obviously the start of my problems and caused irregular performance. Sometimes the car could take mid range trips, other times it'd lose power like before. It would be a few months before this was figured out. Heh.

As a result, a number of other attempts to fix the power problem (which obviously were not the right solutions) ended up being replacements of the fuel filter, coolant temp sensor, and the O2 sensor. At some point I took off the manifold again and realized my mistake and promptly fixed it. However, the car continued to lose power. Further more I noticed a fuel leak. Of course, as soon as I fixed the FPR the car ran wonderfully for about five minutes, reaching every gear and hitting 65 in a 25 (Heh heh). After coming to complete stop, I tried to pull out again but the car immediately began to stall in first gear. After a while I noticed a fuel leak and found it originating from the FPR. I took everything apart today and found that the rubber gasket thing attached too it failed to seal (when I took it off to fix it, I noticed the rubber stuck to the fuel rail and I had to carefully pop it off. This time it came right off with no resistance). I attempted to reseal it put it back together, and the car drove rather well again (As a couple notes, the O2 sensor was replaced because of a dash light code and every time I did a repair like this I disconnected the battery). However, it eventually went back to it's old tricks. Before, the fuel leaked whenever the engine got hot. This time, however, I found no traces of a fuel leak from the FPR like last time, so it must have sealed. In a somewhat desperate move, I quickly ran to the store to grab a new distributor cap and rotor, under the half hearted hope the engine was simply misfiring because of a bad cap (something suggested to me earlier). This also solved nothing. Oh, and then my left blinker stopped working.

What I'm asking is, what am I possibly missing?
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Patrick
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Report this Post10-02-2020 02:09 AM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post

Wow, that's a long first post! Welcome.

Short first response... What's the fuel pressure?
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ltlfrari
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Report this Post10-02-2020 10:04 AM Click Here to See the Profile for ltlfrariClick Here to visit ltlfrari's HomePageClick Here to Email ltlfrariSend a Private Message to ltlfrariEdit/Delete MessageReply w/QuoteDirect Link to This Post
Well first off, welcome to the madness.

Is there a bad eggs smell from the exhaust?
With all your fuel problems it might have been running rich and that can kill a catalytic converter (assuming it has one) which gets clogged up and effectively chokes the car to death as you drive.
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CZSeventyFive
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Report this Post10-02-2020 11:24 AM Click Here to See the Profile for CZSeventyFiveSend a Private Message to CZSeventyFiveEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:


Wow, that's a long first post! Welcome.

Short first response... What's the fuel pressure?


Admittedly it's been a bit since I checked as I've had to borrow a gauge from time to time, but before I fixed the FPR it was reading somewhere around 30 upon start up and then drops to zero and largely stays there. Afterwards the pressure seemed to go to about 60 psi iirc? And I believe it largely stayed there. I guess I'll have to check it again.

And yah, lol, I figured I should be as thorough with this explanation as possible. Cover all the bases.

 
quote
Originally posted by ltlfrari:

Well first off, welcome to the madness.

Is there a bad eggs smell from the exhaust?
With all your fuel problems it might have been running rich and that can kill a catalytic converter (assuming it has one) which gets clogged up and effectively chokes the car to death as you drive.


I haven't noticed any such smells, no. The catcon has been suggested, I think it has one. But it hasn't sounded like it's been running rich (Well, not recently. A while ago, I think right after I replaced the MAP sensor (which I forgot to mention in the first post) it seemed to run rich, but after disconnecting and reconnecting the battery it sounded better.

[This message has been edited by CZSeventyFive (edited 10-02-2020).]

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Patrick
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Report this Post10-02-2020 01:27 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by CZSeventyFive:

...before I fixed the FPR it was reading somewhere around 30 upon start up and then drops to zero and largely stays there. Afterwards the pressure seemed to go to about 60 psi iirc? And I believe it largely stayed there. I guess I'll have to check it again.


Yes, you will... as none of those figures are good.

When you do a fuel pump pressure test, make sure to also note how long the pressure holds after the engine is turned off.
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CZSeventyFive
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Report this Post10-02-2020 04:09 PM Click Here to See the Profile for CZSeventyFiveSend a Private Message to CZSeventyFiveEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hm, the guy who owned the pressure gauge (a professional mechanic, apparently) said it looked good on the last test we did, so maybe it was more than 60. Unfortunately this project has been strung over a couple of months time and my memory is rather poor with details. Regardless I'll check it again. I was also recommended spark plugs and bought some but never installed them since doing so sounds difficult with these and I haven't worked up the courage yet. Might do that today, though.
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CZSeventyFive
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Report this Post10-07-2020 10:23 PM Click Here to See the Profile for CZSeventyFiveSend a Private Message to CZSeventyFiveEdit/Delete MessageReply w/QuoteDirect Link to This Post
I ended up replacing the spark plugs, just to do it, and saw no changes, but I looked at the engine after driving and noticed something pooling kinda down below, I guess. I didn't think to take a picture. I mentioned earlier fuel seemed to be leaking out of the pressure regulator, but now I haven't seen it doing that. So I'm thinking it must be leaking form somewhere else, but I don't know where. What else is generally known to leak? I can try to get a picture of the pooling tomorrow.
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Report this Post10-07-2020 11:03 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by CZSeventyFive:

What else is generally known to leak?


Gasoline, engine oil, transmission fluid, brake fluid, coolant...

If this car sat for a couple years, I wouldn't be surprised (after you running it a bit) that the water pump is now leaking. But it could be anything.

[This message has been edited by Patrick (edited 10-07-2020).]

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Mike in Sydney
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Report this Post10-07-2020 11:09 PM Click Here to See the Profile for Mike in SydneySend a Private Message to Mike in SydneyEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

Yes, you will... as none of those figures are good.

When you do a fuel pump pressure test, make sure to also note how long the pressure holds after the engine is turned off.



Good that you've change the plugs but I'd wager that the problem is with the fuel system. Take it to a mechanic and have the fuel pressure checked. IIRC the fuel rail primes to around 45 PSI and then drops to and maintains around 35 PSI when running. If you're not maintaining this pressure you are probably starving the engine for fuel.

What about the air filter? Is it clean? Is there anything blocking the hose from the filter to the throttle body?
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CZSeventyFive
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Report this Post10-08-2020 11:00 AM Click Here to See the Profile for CZSeventyFiveSend a Private Message to CZSeventyFiveEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Patrick:

Gasoline, engine oil, transmission fluid, brake fluid, coolant...

If this car sat for a couple years, I wouldn't be surprised (after you running it a bit) that the water pump is now leaking. But it could be anything.



Kind of my thought as well as far as sitting goes. It sat for at least two years before I got it, judging by the out of date sticker on the plate. I'm pretty certain it's gasoline based on the smell of the fluid, however, I could be wrong.


 
quote
Originally posted by Mike in Sydney:
Good that you've change the plugs but I'd wager that the problem is with the fuel system. Take it to a mechanic and have the fuel pressure checked. IIRC the fuel rail primes to around 45 PSI and then drops to and maintains around 35 PSI when running. If you're not maintaining this pressure you are probably starving the engine for fuel.

What about the air filter? Is it clean? Is there anything blocking the hose from the filter to the throttle body?


I had replaced the air filter earlier and had checked the path. Everything seemed good as far as that was concerned. I even cleaned out a bit of the throttle body. Those numbers seem more correct to what I observed from the gauge I borrowed, although I think I said 60 earlier. I'm not sure what kind of advanced repairs are needed, or whether or I can even do them. Anything that involves more fuel I probably don't want to do inside my garage or a driveway less I screw something up. I've been thinking about a mechanic, only issue is getting it somewhere. Nearest one from the car is a short drive down long roads, though traffic can be light depending on the time of day. They're almost country roads, though the path would be even shorter if the main road there wasn't shutdown for a bridge repair.

I've noticed disconnecting and then reconnecting the battery seems to give it a good jump for a couple of miles. I've read doing this causes the computer systems to reset, although I'm not sure why this gives it a lasting ride for a short bit. I suppose I could just start and stop it down the road until I get there. :P

I don't recall if I mentioned it before, but this is also the first automotive project that I've ever really undertaken, so it's possible I'm also well over my head. Before this I've only done a few minor repairs to my Volvo, namely jerry-rigging some tail light solutions and wiring a new headlight.
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CZSeventyFive
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Report this Post10-09-2020 03:57 PM Click Here to See the Profile for CZSeventyFiveSend a Private Message to CZSeventyFiveEdit/Delete MessageReply w/QuoteDirect Link to This Post
Alright here's a picture of where its pooling kinda underneath everything. Its definitely oil.
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Report this Post10-09-2020 04:08 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post

Without being there to look around more carefully... I'd guess it might be the distributor O-ring. A very common source of oil leaks on the 2.8 V6.
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CZSeventyFive
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Report this Post10-09-2020 05:47 PM Click Here to See the Profile for CZSeventyFiveSend a Private Message to CZSeventyFiveEdit/Delete MessageReply w/QuoteDirect Link to This Post
Would a leak like this cause power failures like described or is this more likely a different (and likely minor, I'd assume) issue altogether then (if the o-ring/leak is the case, that is)? Unless it's leaked so much oil to cause to problems.
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Report this Post10-09-2020 06:01 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by CZSeventyFive:

Would a leak like this cause power failures like described...?


No.
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CZSeventyFive
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Report this Post10-09-2020 06:15 PM Click Here to See the Profile for CZSeventyFiveSend a Private Message to CZSeventyFiveEdit/Delete MessageReply w/QuoteDirect Link to This Post
Figured, but thought I'd ask. Will have to try it to seal it up anyways.
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Report this Post10-09-2020 07:28 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by CZSeventyFive:

Will have to try it to seal it up anyways.


Don't get a rubber O-ring. It'll just get hard and oil will leak by it again. Get This or one similar locally.

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CZSeventyFive
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Report this Post10-17-2020 04:56 PM Click Here to See the Profile for CZSeventyFiveSend a Private Message to CZSeventyFiveEdit/Delete MessageReply w/QuoteDirect Link to This Post
Ended up looking at it some more, got a fuel pressure gauge to see how it went...was definitely all from fuel pressure losses while driving. Checking the lines on the fuel pump seemed to indicate to the guy who was helping me with this that pressure was unstable on the return lines (?) or something. This was a couple days ago. I don't have a good place to work on that myself for the time being, but I might take it in to a professional for this, see if it's the pump indeed.
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Report this Post10-17-2020 05:06 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by CZSeventyFive:

Ended up looking at it some more, got a fuel pressure gauge to see how it went...was definitely all from fuel pressure losses while driving.


So what were the readings?

 
quote
Originally posted by Patrick:

When you do a fuel pump pressure test, make sure to also note how long the pressure holds after the engine is turned off.

[This message has been edited by Patrick (edited 10-17-2020).]

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