R50/53 Low power, no CEL. Lucky guess solved it!
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4th Gear
Joined: Aug 2019
Posts: 453
Likes: 248
From: Phoenix, AZ
Low power, no CEL. Lucky guess solved it!
TLDR - my R53 has been having loss of power issues lately with no check engine light to help diagnose. I replaced my fuel pump and fuel pressure regulator on a hunch and fixed my car.
Some of you may have followed my thread about my broken coolant tee resulting in a warped cylinder head where I decided to install a used, lower mile engine in my R53.
It was mid May this year when I got my car running again after a 16 week saga of Saturday only work and parts delays, but I was SO happy to be driving my Mini again. That happiness was short lived as my Mini started driving poorly a couple of weeks after that repair.
It started one evening coming home from work. I was coming off the freeway and at the top of the offramp, I had a green light so since I am driving a car that loves to turn, I made that right turn without ever touching the brakes but as I went to accelerate out of the turn, my car would not go. It felt to me like the car was running out of gas. I believe my low gas light had just come on during that drive home, so I explained that away by thinking that hard turn sloshed all the fuel to my side of the car and fuel pump was briefly sucking air. I was not concerned until I thought about it again after I got home. I have owned this car since it was new and I habitually run the fuel level low enough to illuminate the low fuel light (some "experts" say that is a good way to kill a fuel pump but my experience with all the cars I've owned proves that is utter nonsense) and have NEVER experienced that before. Before I made it to a gas station, I had the same "car won't accelerate" out of a right turn (always right turns only) one more time.
I filled the tank and my wife told me she wanted to drive the Mini this week because she, too, missed driving it. She reported back to me later that week that while running errands one day, she had experienced what I had experienced (with fuel level nearly full) and also while cruising straight down the road, she said the car felt like it was going to stall. She didn't want to drive it anymore. After that whole ordeal with the engine replacement, I was not interested in another prolonged episode messing with my car. Without any diagnostics, I ordered a fuel pump and fuel pressure regulator. In driving a high mileage, 19 year old car, I have little concern making an educated guess and throwing some parts at a problem because at worst, I am replacing old, high mileage parts.
I was informed my parts would not ship for about a week and since my parts supplier is across the country from me, I continued to drive my Mini for next 2.5 weeks or so. As I continued driving it, I felt my car usually had a "dead spot" in the RPM range from about 3000 - 3700 RPM where the car felt like it would just choke. At best, it was a noticeable dip in engine power, at its worst, the engine felt like it was about to stall. When it did that I found that if I put the throttle to the floor, I could "power through" that dead spot but even when I did that, the engine power was unimpressive.
My Mini was no fun at all to drive in this condition. One morning on the way to work, I moved into the left lane to pass a rolling roadblock of landscape and construction trucks in the right and middle lanes. I was going maybe 73 MPH with no traffic coming up behind me for about 1/4 mile but the poor power of my Mini was struggling to get around those trucks and a Volkswagen SUV was soon on my rear bumper while my car was struggling to complete the pass. That VW moved into the HOV lane blew past me. It was humiliating.
My Check Engine Light came on about Thursday last week and I was a little excited, thinking there might be a clue as to what is going on when I read the code. I was let down when I found that the code was for a "very small EVAP leak". I replaced my gas cap many years ago for that code, so I just cleared the code and continued driving.
The light came back on and my parts had arrived, so yesterday morning I went into my shop to do the work. I got a small glimmer of hope when I had removed the access panel to my fuel pump (under the LH rear seat) and found a small amount of residue on top of the fuel pump, concentrated around a small, plastic nipple. Interesting, I thought, then I touched that nipple only to have it break off at that slight touch. Well that would be the source of an EVAP leak, so at least now I knew something was going to be fixed today at least.
In anticipation of this repair, I kept the fuel level low so that I wouldn't have to deal with a high fuel level during a fuel pump replacement. My fuel pump replacement went nice a smooth. I moved into the engine bay and removed the intercooler for access to my fuel rail. The fuel pressure regulator faces downward on the fuel rail, so I removed the fuel rail so I could replace the regulator on my workbench. I removed the clip holding it in and had to use my pliers to pull it out of the rail and it just came apart. I had to use a pick and needle nose pliers to dig out the O-rings and the plastic, plunger thing from the fuel rail but overall, that went pretty well too.
When I replaced my thermostat at the conclusion of my engine replacement saga, I broke that pipe that feeds air from the supercharger inlet pipe to the intake air temperature sensor right in front of the thermostat housing. I had ordered (and received) that part weeks ago and wanted to replace that as well. I have been dreading this repair because I knew this pipe runs under coolant hoses and whatnot to plug into that supercharger inlet pipe and I really don't want to tear my car apart again for this. I left the fuel rail off and removed the airbox and was happy to see that I could see where the pipe connects to the inlet pipe, so with the right tools and some luck, I would not need to remove anything else for this. I was pleased that the repair also went pretty smoothly, so I put my car all back together for the road test.
If this repair turns out to not fix my car, I am planning on doing some throttle diagnostics and maybe smoke test the air inlet system for any leaks. My thoughts are a failing throttle should set a check engine light and an air leak should also set a check engine light for lean codes and fuel trims maxed out. My scan tool is able to read some PIDS and I could see my fuel trims were in the low single digits, so I don't think I have an air leak. Anyway, I'll cross that bridge when I come to it. It's time to road test.
I'm driving normally heading out to the freeway while letting the car get up to operating temperature (shouldn't take long in this 110 degree desert heat
) and in this normal driving a light throttle merge onto the freeway (slow traffic in front of me on the on ramp), my car seems to feel ok. A few miles up the freeway, I feel the car should be ready for some load and there is a slight incline in the road now, so I give her some throttle. Seems ok. Optimism building cautiously. A couple more miles up the freeway and it levels out and there is no traffic around me as I'm cruising at 70 mph. I give a big blip of the throttle and downshift to 3rd gear and put the throttle to the floor. OOOh, that's the stuff. She is really pulling hard! I haven't felt that in a while! 
So now I'm at 90 in 3rd gear, so I shift to 6th and coast back down to a legal speed and hit the off ramp where I know there is a road with very little traffic. I make some hard pulls up to 3rd gear. Well, I believe I have fixed my car.
I turn around and head back to the shop. I'm so happy! The final little test is on the loop of the automall where my dealership is located. Last year, after I had replaced my supercharger, I was cruising on that loop at the 25 mph speed limit in second gear when one of the younger techs pulled up next to me in his foxbody Mustang GT (set up for drifting) we looked at each and did a roll race. I was surprised that my little R53 pulled away from him. I'm not saying my R53 will walk away from a foxbody Mustang, but on this 2nd gear roll, I did walk him through second gear. I asked him later but he wouldn't talk to me about it. This is a long way of saying that I replicated that second gear roll in the automall and the immediate throttle response and power level felt right. This is a car I can enjoy driving again.
When I got back home, my wife asked if it was the fuel pump, the fuel pressure regulator or the IAT pipe that fixed the car. I answered that I don't know. I know that the fuel pump had the cracked nipple, so that is what caused the EVAP leak and the resulting Check Engine Light. The IAT pipe that I had rigged together in May might have been an air leak that contributed to these issues, the fuel pressure regulator certainly can cause fueling issues and so can a tired, old fuel pump. In the end, all I care about is that I replaced that rigged IAT pipe (I HATE rigging crap together) and that my car is running strong again after replacing parts that are nearly 20 years old.
I still have new front control arms with polyurethane rear bushings, new ball joints and hardware in the shop waiting for me to install. I've had my eye on a Bilstein B12 suspension kit (Eibach lowering springs with Bilstein B8 dampers) that I'll probably pull the trigger on soon and yesterday when I got home from the shop, I ordered a DDM cold air intake kit. Also on my list of things I want to do are tune by Adrianci and buy/install Miltek headers and exhaust. Then maybe build my old engine into a little beast (bore the block, port/polish the head, performance camshaft, etc...).
Thanks for letting me tell another story. I'll be around and keep the community posted as I keep this daily driven project car running her best.
Some of you may have followed my thread about my broken coolant tee resulting in a warped cylinder head where I decided to install a used, lower mile engine in my R53.
It was mid May this year when I got my car running again after a 16 week saga of Saturday only work and parts delays, but I was SO happy to be driving my Mini again. That happiness was short lived as my Mini started driving poorly a couple of weeks after that repair.
It started one evening coming home from work. I was coming off the freeway and at the top of the offramp, I had a green light so since I am driving a car that loves to turn, I made that right turn without ever touching the brakes but as I went to accelerate out of the turn, my car would not go. It felt to me like the car was running out of gas. I believe my low gas light had just come on during that drive home, so I explained that away by thinking that hard turn sloshed all the fuel to my side of the car and fuel pump was briefly sucking air. I was not concerned until I thought about it again after I got home. I have owned this car since it was new and I habitually run the fuel level low enough to illuminate the low fuel light (some "experts" say that is a good way to kill a fuel pump but my experience with all the cars I've owned proves that is utter nonsense) and have NEVER experienced that before. Before I made it to a gas station, I had the same "car won't accelerate" out of a right turn (always right turns only) one more time.
I filled the tank and my wife told me she wanted to drive the Mini this week because she, too, missed driving it. She reported back to me later that week that while running errands one day, she had experienced what I had experienced (with fuel level nearly full) and also while cruising straight down the road, she said the car felt like it was going to stall. She didn't want to drive it anymore. After that whole ordeal with the engine replacement, I was not interested in another prolonged episode messing with my car. Without any diagnostics, I ordered a fuel pump and fuel pressure regulator. In driving a high mileage, 19 year old car, I have little concern making an educated guess and throwing some parts at a problem because at worst, I am replacing old, high mileage parts.
I was informed my parts would not ship for about a week and since my parts supplier is across the country from me, I continued to drive my Mini for next 2.5 weeks or so. As I continued driving it, I felt my car usually had a "dead spot" in the RPM range from about 3000 - 3700 RPM where the car felt like it would just choke. At best, it was a noticeable dip in engine power, at its worst, the engine felt like it was about to stall. When it did that I found that if I put the throttle to the floor, I could "power through" that dead spot but even when I did that, the engine power was unimpressive.
My Mini was no fun at all to drive in this condition. One morning on the way to work, I moved into the left lane to pass a rolling roadblock of landscape and construction trucks in the right and middle lanes. I was going maybe 73 MPH with no traffic coming up behind me for about 1/4 mile but the poor power of my Mini was struggling to get around those trucks and a Volkswagen SUV was soon on my rear bumper while my car was struggling to complete the pass. That VW moved into the HOV lane blew past me. It was humiliating.
My Check Engine Light came on about Thursday last week and I was a little excited, thinking there might be a clue as to what is going on when I read the code. I was let down when I found that the code was for a "very small EVAP leak". I replaced my gas cap many years ago for that code, so I just cleared the code and continued driving.
The light came back on and my parts had arrived, so yesterday morning I went into my shop to do the work. I got a small glimmer of hope when I had removed the access panel to my fuel pump (under the LH rear seat) and found a small amount of residue on top of the fuel pump, concentrated around a small, plastic nipple. Interesting, I thought, then I touched that nipple only to have it break off at that slight touch. Well that would be the source of an EVAP leak, so at least now I knew something was going to be fixed today at least.
In anticipation of this repair, I kept the fuel level low so that I wouldn't have to deal with a high fuel level during a fuel pump replacement. My fuel pump replacement went nice a smooth. I moved into the engine bay and removed the intercooler for access to my fuel rail. The fuel pressure regulator faces downward on the fuel rail, so I removed the fuel rail so I could replace the regulator on my workbench. I removed the clip holding it in and had to use my pliers to pull it out of the rail and it just came apart. I had to use a pick and needle nose pliers to dig out the O-rings and the plastic, plunger thing from the fuel rail but overall, that went pretty well too.
When I replaced my thermostat at the conclusion of my engine replacement saga, I broke that pipe that feeds air from the supercharger inlet pipe to the intake air temperature sensor right in front of the thermostat housing. I had ordered (and received) that part weeks ago and wanted to replace that as well. I have been dreading this repair because I knew this pipe runs under coolant hoses and whatnot to plug into that supercharger inlet pipe and I really don't want to tear my car apart again for this. I left the fuel rail off and removed the airbox and was happy to see that I could see where the pipe connects to the inlet pipe, so with the right tools and some luck, I would not need to remove anything else for this. I was pleased that the repair also went pretty smoothly, so I put my car all back together for the road test.
If this repair turns out to not fix my car, I am planning on doing some throttle diagnostics and maybe smoke test the air inlet system for any leaks. My thoughts are a failing throttle should set a check engine light and an air leak should also set a check engine light for lean codes and fuel trims maxed out. My scan tool is able to read some PIDS and I could see my fuel trims were in the low single digits, so I don't think I have an air leak. Anyway, I'll cross that bridge when I come to it. It's time to road test.
I'm driving normally heading out to the freeway while letting the car get up to operating temperature (shouldn't take long in this 110 degree desert heat
) and in this normal driving a light throttle merge onto the freeway (slow traffic in front of me on the on ramp), my car seems to feel ok. A few miles up the freeway, I feel the car should be ready for some load and there is a slight incline in the road now, so I give her some throttle. Seems ok. Optimism building cautiously. A couple more miles up the freeway and it levels out and there is no traffic around me as I'm cruising at 70 mph. I give a big blip of the throttle and downshift to 3rd gear and put the throttle to the floor. OOOh, that's the stuff. She is really pulling hard! I haven't felt that in a while! So now I'm at 90 in 3rd gear, so I shift to 6th and coast back down to a legal speed and hit the off ramp where I know there is a road with very little traffic. I make some hard pulls up to 3rd gear. Well, I believe I have fixed my car.I turn around and head back to the shop. I'm so happy! The final little test is on the loop of the automall where my dealership is located. Last year, after I had replaced my supercharger, I was cruising on that loop at the 25 mph speed limit in second gear when one of the younger techs pulled up next to me in his foxbody Mustang GT (set up for drifting) we looked at each and did a roll race. I was surprised that my little R53 pulled away from him. I'm not saying my R53 will walk away from a foxbody Mustang, but on this 2nd gear roll, I did walk him through second gear. I asked him later but he wouldn't talk to me about it. This is a long way of saying that I replicated that second gear roll in the automall and the immediate throttle response and power level felt right. This is a car I can enjoy driving again.
When I got back home, my wife asked if it was the fuel pump, the fuel pressure regulator or the IAT pipe that fixed the car. I answered that I don't know. I know that the fuel pump had the cracked nipple, so that is what caused the EVAP leak and the resulting Check Engine Light. The IAT pipe that I had rigged together in May might have been an air leak that contributed to these issues, the fuel pressure regulator certainly can cause fueling issues and so can a tired, old fuel pump. In the end, all I care about is that I replaced that rigged IAT pipe (I HATE rigging crap together) and that my car is running strong again after replacing parts that are nearly 20 years old.
I still have new front control arms with polyurethane rear bushings, new ball joints and hardware in the shop waiting for me to install. I've had my eye on a Bilstein B12 suspension kit (Eibach lowering springs with Bilstein B8 dampers) that I'll probably pull the trigger on soon and yesterday when I got home from the shop, I ordered a DDM cold air intake kit. Also on my list of things I want to do are tune by Adrianci and buy/install Miltek headers and exhaust. Then maybe build my old engine into a little beast (bore the block, port/polish the head, performance camshaft, etc...).
Thanks for letting me tell another story. I'll be around and keep the community posted as I keep this daily driven project car running her best.
5th Gear
Joined: Aug 2021
Posts: 882
Likes: 343
From: Georgia
Congrats on getting it fixed!
I know of nothing better than a great running Mini! I just did the front end stuff on my Cabriolet and it rides fantastic! When my fuel pump on my R50 was on its last leg I was getting lean codes.
I know of nothing better than a great running Mini! I just did the front end stuff on my Cabriolet and it rides fantastic! When my fuel pump on my R50 was on its last leg I was getting lean codes.
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