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Discussion Starter · #1 ·
Hello everyone,

I was hoping you could help me out. I just bought a 2005 MDX with 190,000 miles on it. The timing belt had snapped and it ended up bending a couple of valves. We tore the whole top of the engine apart and replaced the heads completely and put the whole thing back together. The car ran great when we got it all back together. But then after about a month, it became harder to start in the mornings. The only codes it would show were P0300, P0301, P0302, P0303, P0304, P0305, and P0306. So I figured I might as well change the sparkplugs since I didn't know when they were last changed. I also checked the coil packs and all of those looked good and I even swapped those out with another set I had. The same issue kept happening and it became harder and harder to start. So we pulled the engine apart again just to see if we missed anything as well as check the position of the timing belt. Since we had the engine apart we swapped in a new crankshaft positioning sensor even though the old one looked fine. The timing belt was right where it needed to be so we put it all back together. We bought a new diagnostic scan tool and the only thing that was out of range was the fuel level input, which the fuel gauge was totally accurate but we had gone through everything else and we knew it was getting spark so we started to make sure it was getting fuel. When you turned the key on you could hear the fuel pump kick on and then you could also hear the fuel pump relay click off so I figured both of those were good. Then I read that the battery could be the culprit even though it cranked over someone on this forum said it might not have enough battery to power all of the other electrical components you need to start the car so we bought a new battery and it started instantly until about 2 hours later when I tried starting it. On that same forum, someone said it could be the fuel regulator which is built into the fuel pump itself so I just replaced that and it is still having troubles starting.

Let me know if you have any ideas.

Thank you
 

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Hello I have a 2003 mdx 167,000 miles. 2020 replaced tires, battery, rotors, brakes. 2021 replaced timing belt, serpentine belt, water pump, sensor, pulley, filters, ground cable, differential oil, upper & lower motor gaskets, upper motor mount, radiator cap, trans dip stick. In the following week started smelling gas fumes, gas mileage went from 13.5 to 6 miles per gallon and it started to pull when changing gears. The mechanic said he could not find any thing wrong. Two months later the timing belt broke. Driving home all the light on dash came on and it lost power. The towing company said the crank shaft was hard to turn and the cam shaft MIGHT have snapped the timing belt. Now they're saying it might be motor failure. I out of over 5 thousand and I have been offer 650 dollars to sell the car. I don't know what to do. My advice is to check the alternator, starter, if anyone is interested in a 2003 for parts sent me a message. Good luck to you.
 

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To the OP, so the new battery totally solved your problem for 2 hrs and then the hard to start condition came back???

What does hard to start mean - turns over but no start, doesn’t turn over, starts but stumbles?

When you say you changed the fuel regulator, did you change the entire fuel pump assembly? Did you do a pressure check on the fuel line at rest and with the engine running?

Note that the pump assembly has a fuel filter, pressure regulator (which sounds like you changed) and a fuel pump. With that many miles, the filter could be restricting flow and/or the pump could be at a point where it won’t hold pressure.
 

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Discussion Starter · #4 · (Edited)
Hi LeftOverParts,

The new battery seemed to have solved the problem and then after a couple of hours after the last successful start we went to start it and it would just turn over and not start like before. And yes I changed the entire fuel pump assembly with the pump, filter, and regulator. I did not do a pressure check on the fuel line though. I can hear the pump working when I turn the key to the on position. Also, the only way I can get it to fire and stay running is to apply pressure to the gas pedal which I know you are not supposed to do with fuel injection but it is still hit and miss using this method as well. I didn't mention this in my original post.
 

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It’s a little hard to follow what happened and how it’s running but assuming the battery is still fully charged and the fuel pump and fuel system are good, I’d check vacuum lines and intake assembly to ensure no leaks (since it sounds like you probably removed the intake). If no leaks or loose bolts, clean the throttle body and map sensor.

if that doesn’t work, I’d check compression. I’m saying that bc it sounds like, you removed the replaced heads and then reassembled it. I’m wondering if a head gasket went out.

Good luck!
 

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Hi LeftOverParts,

The new battery seemed to have solved the problem and then after a couple of hours after the last successful start we went to start it and it would just turn over and not start like before. And yes I changed the entire fuel pump assembly with the pump, filter, and regulator. I did not do a pressure check on the fuel line though. I can hear the pump working when I turn the key to the on position. Also, the only way I can get it to fire and stay running is to apply pressure to the gas pedal which I know you are not supposed to do with fuel injection but it is still hit and miss using this method as well. I didn't mention this in my original post.
AFTER TAKING MY '05 MDX TO DEALERSHIP FOR DIAGNOSTIC'S OF SIMILAR ISSUES AS YOURS, I WAS TOLD IT IS THE "HANDS FREE" THAT DRAINS THE BATTERY & AFTER COMPLETELY DISCONNECTING IT, MY MDX NEVER HAD ANY MORE ISSUES WITH STARTING OR ANY OTHER POWER PROBLEMS!!

HOPE THIS HELPS & GOOD LUCK
 
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