This relates to a 2003 Mustang GT, no major mods, just a standard stock '03 GT. Also, I apologize for the long post but I feel like context is needed.
I will preface this to show how I got to where I am:
Back in 2017/2018 my fuel tank was rusted and causing a leak. I replaced the tank, moved the valves over, etc. put in a new fuel pump. I cannot recall what brand of pump -- it wasn't nice but also wasn't incredibly cheap. Everything is fine. My old pump was working, but it was a 15 year old stock pump at that time, I felt better to replace it while I had the tank out.
Fast forward to late 2022/early 2023. I start having issues (especially when making a hard turn and when fuel is getting under half a tank) where the car will sputter and try to die. Does okay with fuel topped off. I figure the "okay" fuel pump I purchased in 2017/18 was the problem, so I again replace the fuel pump. This time I went pretty cheap. Maybe $120 or so for the whole assembly -- I was telling myself I would be buying a new vehicle soon, so cheap will last until then when the Mustang becomes a project car. I slap it in there and the problem goes away.
Fast forward again to a month and a half ago. Car is running fine one day, I think I was down to maybe half a tank of gas drive the car, go home park it. I go outside the next evening, try to start it -- it cranks but won't fire up. I notice I don't hear the pump priming at all, so I pull the fuel line from the rail and turn the key, sure enough no fuel. This time I just think because I cheaped so much on the last pump that this is what I get and it already died. So, I again drop the tank and replace the pump. This time I don't cheap out and I get a Walbro TU229HP (255 LPH) -- pretty common pump. I install it, care fires right up, no problem -- runs just fine.
Now, we get to the other day -- the car has been running fine for about a month and a half now. Friday everything is fine, I fill up the tank (which is awesome considering I may have to drop the tank again) that night go home. Saturday, everything is fine, I drive at least once. Then Sunday I go out in the morning and try to start it, it cranks for a long time, won't start. I throw my hands in the air thinking that ANOTHER pump has died. I give it one more try, it turns over and runs just fine for the trip to where I was going and back. It started up just fine for the return trip. Later Sunday night, I start it up again, no problems. This time while driving I make a left turn onto a higher speed road, start to hit the gas and it just completely bogs down and dies. So I'm stuck in the road -- I turn it over a few times and it will start and either immediately die, or die the moment I touch the gas. I spent 3-5 minutes trying to get it going, eventually I do (this is probably completely unrelated, and I don't recall if I did this before or after I successfully got it running enough to get it out of the road, but I turned off the A/C). I park it in a hotel parking lot 20 feet from where it died for the night as it was late and didn't want to deal with trying to get it home at that moment.
The next day I go back to get it. It starts right up, maybe a slightly longer crank -- runs very poorly. Rough idle, constantly bogs down when I give it gas -- I'm having to finesse it the whole way back, but it never dies on me.
I get back to my house, get it in the garage and go grab my diagnostic tools. I pull codes and check fuel pressure. Pressure was VERY low. At idle is was sitting just under 10 PSI*. The only codes showing up where Cylinders 1 and 5 misfires. I decide with the information I have to wait till tomorrow (now today) to start messing with things.
Today, I go out and just first thing try to start it up to verify that the fuel pressure I saw last night was accurate. It cranks and cranks and cranks and won't start. Pump is once again not priming. I do my usual disconnect of the fuel lines to see if anything comes out. Nothing. I tell myself that there HAS to be something else wrong -- this many pumps in this short of a time is not right obviously. I check the pump fuse, I get out the multi-meter and start checking voltage at connections. Everything is fine, there is power going to the pump. Frustrated I plug the pump back in, not expecting anything to happen I put the key in and turn it, and the pump primes. I do this a couple more times to make sure it wasn't a one time fluke. I hook the fuel line back up and start the car up just fine. I check the fuel pressure and it is priming to about 60 PSI* then idling around 40 PSI*. No misfires, no stutters, just running exactly how it should. I did notice that pressure drops off pretty quick when I shut it down, it doesn't go straight to 0 but within maybe 2 minutes it was already under 20 PSI. I assumed it would hold higher pressure longer.
After Googling, I know there are many things to check (CCRM, FPDM, FRPS, possibly some electrical connection somewhere? Or the IFS switch going bad? I also made sure it wasn't triggered) -- has anyone encountered something like this before? I know a lot of people will think it's just the pump -- and I know it is entirely possible I got unlucky and got a dud, but I don't think a car should go through this many pumps in 7-8 years? Also, I never got a CEL for anything this entire time. I'm thinking about replacing the FPDM either way, it's cheap and I can get to it quickly, even though I believe you generally get a code for a FPDM issue.
* Fuel Pressure was measured via OBD2 and app, but, based on how the car was running before and after I believe it was correct.
- No fuel present in the FRPS vaccum line.
Again, sorry for the long post, but this car has been frustrating lately. I appreciate any possible help. Let me know if you need additional information -- I may be forgetting things I have done or checked right now.
TLDR;
I'm on my (possibly) 3rd dead/dying fuel pump in 7/8 years. Latest fuel pump wasn't cheap. Suddenly car started bogging down, low fuel pressure, rough idle -- all within one day after 1.5 months on a brand new fuel pump (long crank to get it started earlier in the day but was fine for a while). Fuel pressure showed just under 10 PSI at idle. Next day while doing diagnostics, disconnecting and reconnecting the fuel pump harness magically fixed the problem. Clearly there is still a problem but trying to figure out the best approach.
I will preface this to show how I got to where I am:
Back in 2017/2018 my fuel tank was rusted and causing a leak. I replaced the tank, moved the valves over, etc. put in a new fuel pump. I cannot recall what brand of pump -- it wasn't nice but also wasn't incredibly cheap. Everything is fine. My old pump was working, but it was a 15 year old stock pump at that time, I felt better to replace it while I had the tank out.
Fast forward to late 2022/early 2023. I start having issues (especially when making a hard turn and when fuel is getting under half a tank) where the car will sputter and try to die. Does okay with fuel topped off. I figure the "okay" fuel pump I purchased in 2017/18 was the problem, so I again replace the fuel pump. This time I went pretty cheap. Maybe $120 or so for the whole assembly -- I was telling myself I would be buying a new vehicle soon, so cheap will last until then when the Mustang becomes a project car. I slap it in there and the problem goes away.
Fast forward again to a month and a half ago. Car is running fine one day, I think I was down to maybe half a tank of gas drive the car, go home park it. I go outside the next evening, try to start it -- it cranks but won't fire up. I notice I don't hear the pump priming at all, so I pull the fuel line from the rail and turn the key, sure enough no fuel. This time I just think because I cheaped so much on the last pump that this is what I get and it already died. So, I again drop the tank and replace the pump. This time I don't cheap out and I get a Walbro TU229HP (255 LPH) -- pretty common pump. I install it, care fires right up, no problem -- runs just fine.
Now, we get to the other day -- the car has been running fine for about a month and a half now. Friday everything is fine, I fill up the tank (which is awesome considering I may have to drop the tank again) that night go home. Saturday, everything is fine, I drive at least once. Then Sunday I go out in the morning and try to start it, it cranks for a long time, won't start. I throw my hands in the air thinking that ANOTHER pump has died. I give it one more try, it turns over and runs just fine for the trip to where I was going and back. It started up just fine for the return trip. Later Sunday night, I start it up again, no problems. This time while driving I make a left turn onto a higher speed road, start to hit the gas and it just completely bogs down and dies. So I'm stuck in the road -- I turn it over a few times and it will start and either immediately die, or die the moment I touch the gas. I spent 3-5 minutes trying to get it going, eventually I do (this is probably completely unrelated, and I don't recall if I did this before or after I successfully got it running enough to get it out of the road, but I turned off the A/C). I park it in a hotel parking lot 20 feet from where it died for the night as it was late and didn't want to deal with trying to get it home at that moment.
The next day I go back to get it. It starts right up, maybe a slightly longer crank -- runs very poorly. Rough idle, constantly bogs down when I give it gas -- I'm having to finesse it the whole way back, but it never dies on me.
I get back to my house, get it in the garage and go grab my diagnostic tools. I pull codes and check fuel pressure. Pressure was VERY low. At idle is was sitting just under 10 PSI*. The only codes showing up where Cylinders 1 and 5 misfires. I decide with the information I have to wait till tomorrow (now today) to start messing with things.
Today, I go out and just first thing try to start it up to verify that the fuel pressure I saw last night was accurate. It cranks and cranks and cranks and won't start. Pump is once again not priming. I do my usual disconnect of the fuel lines to see if anything comes out. Nothing. I tell myself that there HAS to be something else wrong -- this many pumps in this short of a time is not right obviously. I check the pump fuse, I get out the multi-meter and start checking voltage at connections. Everything is fine, there is power going to the pump. Frustrated I plug the pump back in, not expecting anything to happen I put the key in and turn it, and the pump primes. I do this a couple more times to make sure it wasn't a one time fluke. I hook the fuel line back up and start the car up just fine. I check the fuel pressure and it is priming to about 60 PSI* then idling around 40 PSI*. No misfires, no stutters, just running exactly how it should. I did notice that pressure drops off pretty quick when I shut it down, it doesn't go straight to 0 but within maybe 2 minutes it was already under 20 PSI. I assumed it would hold higher pressure longer.
After Googling, I know there are many things to check (CCRM, FPDM, FRPS, possibly some electrical connection somewhere? Or the IFS switch going bad? I also made sure it wasn't triggered) -- has anyone encountered something like this before? I know a lot of people will think it's just the pump -- and I know it is entirely possible I got unlucky and got a dud, but I don't think a car should go through this many pumps in 7-8 years? Also, I never got a CEL for anything this entire time. I'm thinking about replacing the FPDM either way, it's cheap and I can get to it quickly, even though I believe you generally get a code for a FPDM issue.
* Fuel Pressure was measured via OBD2 and app, but, based on how the car was running before and after I believe it was correct.
- No fuel present in the FRPS vaccum line.
Again, sorry for the long post, but this car has been frustrating lately. I appreciate any possible help. Let me know if you need additional information -- I may be forgetting things I have done or checked right now.
TLDR;
I'm on my (possibly) 3rd dead/dying fuel pump in 7/8 years. Latest fuel pump wasn't cheap. Suddenly car started bogging down, low fuel pressure, rough idle -- all within one day after 1.5 months on a brand new fuel pump (long crank to get it started earlier in the day but was fine for a while). Fuel pressure showed just under 10 PSI at idle. Next day while doing diagnostics, disconnecting and reconnecting the fuel pump harness magically fixed the problem. Clearly there is still a problem but trying to figure out the best approach.
