Feels like downshifting while driving in 5th

[mr_maxime]

I'm in the middle of driving to my dad's house and the car hit a point where it felt like I downshifted. I keep going and now it's getting worse. I pulled over cause im worried about getting stranded on the side of the road. Is my clutch going out?

[Bitsyncmaster]

Your engine is probably loosing power rather than thinking the clutch is slipping in 5 th gear. When a clutch slips, your RPM increase without seeing speed increase.

[mr_maxime]

What could be causing that? I'm about 60 miles from home now

[Bitsyncmaster]

I'm guessing it happened suddenly. Just guessing something happened to the lambda and now your engine is running lean to cause power loss. Do you still have a stock RPM relay? Do you have any tools with you?

[mr_maxime]

Stock rpm relay and I got some open end wrenches. I'm currently at a truck stop.

[Bitsyncmaster]

Can you tell if the FV is buzzing when the engine is running? Since I'm just guessing the lambda stopped, would not want to suggest a fix if it's working anyway.

[mr_maxime]

What is the FV?

Also picture of the rpm relay. 2 prongs look somewhat toasty
http://i.imgur.com/2OF9kRK.jpg

[Bitsyncmaster]

FV is frequency valve. Under the air cleaner on passenger side valve cover. If it's not buzzing (engine running) try banging that RPM relay a little and see if it buzzes after you do that.

[mr_maxime]

Will do. In the meantime, this probably isn't helping. I did try finding one at parts store a while ago but no match

https://imgur.com/oycK1RB

I beat a lot of dust out of it as well

[Bitsyncmaster]

A 60 mile drive home without the air cleaner probably would not hurt anything.

[mr_maxime]

Fv is buzzing

[Bitsyncmaster]

OK, then it's not the lambda failing. Was the problem sudden, intermittent or did it start loosing power slowly?

[mr_maxime]

Sudden while going uphill. I was around 2.5-3k rpm. Then I started happening more often.

[Bitsyncmaster]

It may just be your fuel pump since you were under a high load condition. I would just try the drive home unless it gets really bad. Maybe a good idea to fill the tank also.

[mr_maxime]

Tank was filled. I shoehorned an air filter in. I drove several miles without and problem didn't reoccur but now my car just stalled out in the middle of i75. Rpm relay feels very rpm relay is very hot.

[mr_maxime]

I was about to start the car back up and get to the shoulder. The car then died while I was inspecting it.

[mr_maxime]

I think the fuel pump is dead. It's screams like hell when I turn on the car. It got replaced by dmc in 2015 with their older style.

[mr_maxime]

Here's a clip. Car starts, runs for a bit, fuel pump starts screaming and car dies.

https://youtu.be/Ye5Ce1B7P7k

[David T]

Here's a clip. Car starts, runs for a bit, fuel pump starts screaming and car dies.

https://youtu.be/Ye5Ce1B7P7k


How hot is it by you? If it is very hot, the pick-up hose may be collapsing causing fuel starvation and the pump would also be noisy. Inspect the pick-up hose and maybe put a spring inside.

[mr_maxime]

Car has cooled off and it seems to be idling ok. It was 90ish out and I had been driving for maybe 50mins. It is very likely heat related. Which one is the pick up hose? Driver or passenger side?

Edit: also a lot less noisey. Not sure how hot the rpm relay is supposed to be but it was nearly untouchable when car died. New dmch pump and solid state relay might be good investment.

[David T]

Car has cooled off and it seems to be idling ok. It was 90ish out and I had been driving for maybe 50mins. It is very likely heat related. Which one is the pick up hose? Driver or passenger side?

Edit: also a lot less noisey. Not sure how hot the rpm relay is supposed to be but it was nearly untouchable when car died. New dmch pump and solid state relay might be good investment.

The pick-up hose is inside the fuel tank connecting the baffle and the fuel pump. Kind of an "S" shaped, black hose about 18" long.

[Bitsyncmaster]

That's the old common fuel pump whine. It happens when the gas in the tank starts going above 120 deg. F. I had the same whine and I had the spring in the pickup hose. So it's not just a problem with the pickup hose. I installed a fuel cooler and the problem never returned but that was before DMCH had that new pump. So I would just go with the new type pump when you get it home.

If your not home yet, you may be better off waiting till it cools off later this evening to try the drive then.

[mr_maxime]

It's at my dad's now. I'll get a rental for the work week while waiting on the pump to arrive. I'm not risking getting stranded.

How hot are rpm relays supposed to be?

[Bitsyncmaster]

It's at my dad's now. I'll get a rental for the work week while waiting on the pump to arrive. I'm not risking getting stranded.

How hot are rpm relays supposed to be?

The stock RPM will run very hot normally. That's one of reasons my first product was the solid state RPM relay. If you think the black case it hot, open the unit up and touch the relay coil. Don't really do that, you will burn your fingers. The relay coil is what produces the most heat.

[David T]

The stock RPM will run very hot normally. That's one of reasons my first product was the solid state RPM relay. If you think the black case it hot, open the unit up and touch the relay coil. Don't really do that, you will burn your fingers. The relay coil is what produces the most heat.

Putting a spring into the pick-up hose will prevent the fuel starvation problem but once the pump makes that noise, it is damaged and will continue to make noise. Eventually it will fail so replacing it is a good idea. The newer style combo pump unit is nice but pricey and there have been some reports of problems with them, the fuel sender and hot restart problems. I think they have cured them now.

[mr_maxime]

Drove the car around this morning. Fuel pump wasn't screaming.

I drive the car daily and had not had any issues but my drive is about 25 mins now. This is the first time I've driven it this far in 90 degree weather. My guess is that it was hot fuel causing starvation, but I'll be cautious and replace it with the new pump.

[Bitsyncmaster]

Drove the car around this morning. Fuel pump wasn't screaming.

I drive the car daily and had not had any issues but my drive is about 25 mins now. This is the first time I've driven it this far in 90 degree weather. My guess is that it was hot fuel causing starvation, but I'll be cautious and replace it with the new pump.

What happens is the fuel pump provides more fuel than necessary and the returned fuel to the tank is about 1 or 2 degrees warmer than the fuel pumped from the tank (I did measurements to find that out). The heat comes from the extra fuel piped around that hot engine. So it takes about an hour or more of driving for the gas in the tank to reach above 120 degrees (I tested that also). That is the temperature my pump would start buzzing.

So far I've not heard of any buzzing complaints with the new style DMCH pump.

[David T]

What happens is the fuel pump provides more fuel than necessary and the returned fuel to the tank is about 1 or 2 degrees warmer than the fuel pumped from the tank (I did measurements to find that out). The heat comes from the extra fuel piped around that hot engine. So it takes about an hour or more of driving for the gas in the tank to reach above 120 degrees (I tested that also). That is the temperature my pump would start buzzing.

So far I've not heard of any buzzing complaints with the new style DMCH pump.

The fuel gets heated by several different ways. The hot air coming out of the radiator, the cooling system piping running along the bottom of the tank, the fuel pump itself and the hot motor. One trick is to wrap a coil of tubing around the accumulator and run the fuel through that to cool it. Another is a big piece of thick rubber to deflect the air coming out of the radiator down and away from the fuel tank.

[Bitsyncmaster]

The fuel gets heated by several different ways. The hot air coming out of the radiator, the cooling system piping running along the bottom of the tank, the fuel pump itself and the hot motor. One trick is to wrap a coil of tubing around the accumulator and run the fuel through that to cool it. Another is a big piece of thick rubber to deflect the air coming out of the radiator down and away from the fuel tank.

I had that rubber deflector and the pump was still buzzing. Yes, I was the guy that made the cooler wrapping pipe around the accumulator. That's what cured the problem.

[David T]

I had that rubber deflector and the pump was still buzzing. Yes, I was the guy that made the cooler wrapping pipe around the accumulator. That's what cured the problem.

Once you starve the old style pump of fuel and it starts making noise, you have damaged it internally and it will always be noisy and fail prematurely. The fuel cools and lubricates the pump, when you run the pump and fuel does not go through it because the hose has collapsed (or kinked), the parts inside the pump wear out quickly. The old style OEM set-up with that rubber pick-up hose is VERY susceptible to kinking and collapsing and when it does you lose fuel pressure and damage the fuel pump. That fuel pump moves a LOT of fuel and can create quite a bit of suction. When the fuel gets hot, so does the hose and it gets soft and can easily collapse or kink if, when you install the pump, you turn it and twist the hose and make it tend to kink. My "cure" is to put a spring inside the hose to keep it from collapsing. It's been working fine for me for years. And all of the cars I have installed the spring in. The coil around the accumulator is OK but you have to worry if a rock could damage it and it reduces the amount of cooling available in the cabin a little. I suppose you could wrap the coil with some insulation to protect the tubing from damage and maybe regain some of the losses from the absorption of heat from the fuel. The rubber deflector also is a big help behind the radiator. Ultimately the fuel WILL heat up a lot. The newer style pump from DMCH may be better at handling heat, I don't know. Maybe insulation around the two cooling pipes running under the tank would also help. I think that's where the majority of the heat comes from. Bottom line, if your old style pump is making noise you have problems. Probably why the #7 fuse also melts. When that pump gets noisy it is going to be drawing more current.

[Josh]

certainly sounds like you need a new fuel pump to me.

[Nicholas R]

certainly sounds like you need a new fuel pump to me.

I agree. The pump died while driving; how much more evidence is needed?

Either replace it, or keep a spare on hand and be ready to change it on the side of the road.

I've limped around on fuel pumps that overheated, shut down, then cooled and ran again, but in the end they still always end up needing replaced.

[mr_maxime]

I'm replacing my pump now and the instructions say to clean the tank. There is a note that if the bottom feels "gritty" then it is not clean. Ive cleaned a good but, there wasn't all that much junk however the bottom feels gritty. It seems like this is the texture of the tank though.

https://imgur.com/blXzEcK

[Delorean Industries]

Texture is normal. That is getting cleaner but needs some work. Get the little rust spots and minor debris out. The new pump pick up will clog with those contaminates.

[mr_maxime]

I'm getting a shop vac to vacuum out the bits. I've been using a white rag and acetone, and the rag wasn't getting dirtier.

[mr_maxime]

I've got everything hooked up, but the return line is a bit kinked. I routed the supply line differently than the directions because I couldn't route it as instructed without a massive kink.

https://imgur.com/a/r6iS0