89 Daytona losing power

[Force Fed Mopar]

Could be a TPS issue also.

[83scamp]

About a year ago I sold my GLHT which had been sitting for a few years.

The new owner had essentially the same problem you describe. It turned out to be a still dirty gas tank. He had installed a new fuel pump and cleaned the tank.

But the car would fall flat on its face after driving a short distance. He would turn the car off and when he restarted it, it would run "normal" for a while. After checking everything, he pulled the fuel pump to check it. The sock was filthy. So he drained the gas and cleaned the tank again, still getting a lot of grime and stuff out of it.

He put it all back together and drove the car some more, but after a few miles the problem returned. He pulled the pump again and the sock was dirty again. So he pulled the tank off the car, washed it well with soap and water, scrubbing the bottom and as far in as he could reach. He rinsed the tank with his pressure washer and said the amount of stuff that came out of it was unbelievable.

He let the tank sit in the sun to heat it up and dry it out and put it back in the car. The problem was gone and hasn't returned.

He figured that the pump would get enough clean gas to go a few miles but would start sucking up the grime till it finally clogged. It would idle fine but would not make any power. If he turned the engine off for a bit, enough grime would fall off the sock to allow it to run again when restarted, but as soon as enough grime was sucked up, it would clog the sock again.

Barry

Thanks Barry, I'm thinking I may just pull the pump again and have a look. It's not that tough to get out.

Could be a TPS issue also.

I've considered that as well. I need to see how to back-probe it and see if there are any issues.

Also, looking around last night, I discovered that there is a hose missing that goes from the 3-way PCV rubber connector on the valve cover to the air filter housing. I'm going to try and make something to go in it's place, could that be part of it? Looks like it's just a barb to draw fresh air, so I can't imagine it's creating an issue, but one more thing I need to fix...

[Force Fed Mopar]

Also, looking around last night, I discovered that there is a hose missing that goes from the 3-way PCV rubber connector on the valve cover to the air filter housing. I'm going to try and make something to go in it's place, could that be part of it? Looks like it's just a barb to draw fresh air, so I can't imagine it's creating an issue, but one more thing I need to fix...

Nope, that will not cause any issues, other than a little oil seepage

[83scamp]

OK, didn't think so, but figured I'd ask...

[83scamp]

OK, I'm making progress. It is fuel pressure related. Not sure what is causing it, but fuel pressure definitely drops when it loses power.

I went for a nice drive tonight, and here is what I observed:

Starts out fine, about 55 psi. If I accellerate at a "normal" rate, pressure goes up, and it seems to run OK. When I get into boost, that is when trouble starts. The more boost it builds, the lower the pressure goes. If I get out of the gas, it will go back up to 55 psi. So does that mean FPR? I notice when I start having issues, I can hear the pump whining. Doesn't necessarily relate to lower pressure, but I know the pressure will drop at some point when it's whining. I'm going to pull the pump and see if the sock is plugged.

Other than that, I assume it could be a bad FPR? I'm going to pull the vacuum line and see if I get fuel out of it.

[83scamp]

Pump sock is clean. I bench ran the pump, and it sound OK, but I do notice a little pulsing sound as it runs? Not sure if that is normal. Don't want to run it dry too much.

I get good vacuum to the FPR, it holds vacuum when applied to it. And I didn't get any fuel out of the FPR vacuum line. So I have to assume the diaphram is intact.

Too late for a drive tonight, it's dark, and I couldn't see the guage if I tried. I'll see if I can rig up a T tomorrow at work so I can check pressure in front of the FPR...

I was really hoping to find a "smoking gun" tonight.... Oh well...

[c2xejk]

If the fuel filter is not clogged or other restriction on the supply side, then likely the pump is bad (can't provide enough flow at pressure.)

[83scamp]

If the fuel filter is not clogged or other restriction on the supply side, then likely the pump is bad (can't provide enough flow at pressure.)

That's what I'm kind of leaning towards. I want to check pressure in front of the FPR tomorrow as a double check. If it dips off there, I'm pretty certain it's the pump...

[RattFink]

I've seen a lot of pumps fail like this, I know it's new but that doesn't mean it's any good. I've been bit by brand new parts being bad before.

[turbovanman²]

Check the fuel pressure, then remove the FPR hose, if it goes up, the FPR is most likely fine, if it doesn't change then its bad. Also check the vacuum hose for a fuel smell. It does sound like a bad pump though.

[83scamp]

Well, I went back out last night, and I think I found my "smoking gun".

I decided to pull the pump off the hanger and start checking things out. As I was removing the screws that hold the plastic basket onto the hanger, one of the power wires snaps off. So obviously, it wasn't getting full current through the pump. But wait, it gets better...

I go to pull the pump off, and the brass nipple in the damper comes out with it. The hillbillies had twisted it out of the damper, and thought just shoving it back in the hole was good enough.

Then, I remove the pump from the plastic basket, and they didn't put the seal in between the pump and the plastic end cap, nor did they put the seal on between the sock and the end cap. So my guess is, this thing has been sucking fuel from everywhere but where it was supposed to, and blowing it out in the tank in front of the damper...

So, today I'm going to search through our o-ring drawer at work for correct sizes to use as seals, and for now, I've removed the damper and will see how it builds pressure tonight. I also cut the ends off both power wires, and correctly crimped on new spade terminals...

[turbovanman²]

Throw the damper away, just use a piece of the proper rated hose for submersion. I think its an R10 hose, Napa carries it.

[83scamp]

Well, spent 3 hours on it last night, and the net result: No change...

Fixed the pump wiring, replaced the missing o-rings on the cap, eliminated the damper. Tested great in the garage. 55psi static, 20"hg vacuum, pressure dropped to 48 psi, 10psi pressure, and I got 70 psi at the rail. Bumped it up to 20 psi at the regulator, and fuel rail went up to 80 psi. Held it there for 2 minutes trying to get the pump to screw up, held steady... Took it for a drive, first time I hit boost, and fuel pressure drops like a rock, and it falls flat on its face... Makes me want to scream...

Once it acts up, I can control the fuel pressure at will with my right foot. Step on the gas, and fuel pressure drops. Lift off, and in 2-3 seconds it goes right back up to 55psi... I just don't get it. I manually activated the ASD relay in the garage and let the pump run for 10 minutes, did all of the above tests. Never even bobbled. Go for a drive, and 2 minutes out, it won't hold pressure...

I've got a manual boost gauge coming today, I'm going to T that into the line for the regulator and go for a drive to see how the two pressures compare. If that tests fine, I think I'm going to replace the pump...

[Force Fed Mopar]

Bad pump. Put a real Walbro 255 in it and be done.

[bigbarneycars]

It's almost the weekend my friend. Walk away from it for a couple days and then look at it with fresh eyes and a rested brain, Jer

[83scamp]

It's almost the weekend my friend. Walk away from it for a couple days and then look at it with fresh eyes and a rested brain, Jer

Yep, but it's my weekend to work, so no rest for the wicked...

[jonnymopar]

You sure there's no junk in that tank? If there was some gunk (or, with the sound of these hillbillies, it could be anything), then that may explain why it's only happening when you drive it. With the car in the garage, manually operating the pump, the obstruction could have been sitting out of the way. Slosh things around on a road trip, and it falls into place. Just a guess.

+1 for the Walbro though. Mine's been working beautifully for 7+ years now.

[83scamp]

You sure there's no junk in that tank? If there was some gunk (or, with the sound of these hillbillies, it could be anything), then that may explain why it's only happening when you drive it. With the car in the garage, manually operating the pump, the obstruction could have been sitting out of the way. Slosh things around on a road trip, and it falls into place. Just a guess.

+1 for the Walbro though. Mine's been working beautifully for 7+ years now.

I'm sure. Pulled it myself and cleaned it out. When I pulled the pump Tuesday night, the sock was clean. I have a couple more things mentioned above to check tonight. If those check out, I think it's time for a new pump.

[EaZyE426]

A pump being able to output correct pressure while the car is off doesn't seem like a very good test imo. The question remains if the pump can put out the pressure while still delivering the flow required. With the car off, it's not actually pumping fuel, just increasing pressure

[83scamp]

A pump being able to output correct pressure while the car is off doesn't seem like a very good test imo. The question remains if the pump can put out the pressure while still delivering the flow required. With the car off, it's not actually pumping fuel, just increasing pressure

And I will agree with you. But that's the test in the FSM for fuel issues. In fact, if I were to strictly follow the FSM, Chrysler says there is nothing wrong with my pump, or fuel system. Obviously, that's not the case...

A couple more tests tonight, and then I'm probably going to end up with a new pump... I'll update later...