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Fuel pump and relay
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kidmoe
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PostPosted: Wed Feb 14, 2018 7:57 pm    Post subject: Fuel pump and relay Reply with quote

Still trying to get my 98 MPV running. Pretty sure I have it narrowed down a bit with the help of vincentkou98 and once I recover from having the flu I plan on finishing my tuneup with a new cap and rotor. I'm keeping my fingers crossed that this works.
I do however have another question about the fuel pump and relay. While I was trying to diagnose why my MPV would not start, I was going through the fuel system to search for problems. I found out that when the key is in the "on" position, the pump does not prime and the relay does not click. When I actually turn the key and try to start the vehicle the relay clicks and the fuel pump works as it should.
Is this the way this should work? I was under the impression that the pump primes gas when the key is in the "on" position. Could it be an issue with the relay, or maybe something else?
I have the MPV running now but it idles super rough and stalls. Like I said, next step is cap and rotor, but I just wanted to see if anyone had an opinion on if this is an issue that I should investigate further. Thanks!
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chaseNYC
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New '98 and feelin' great
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Joined: 21 Jul 2003
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Location: Brooklyn, NY, USA, Planet Earth

PostPosted: Wed Feb 14, 2018 10:55 pm    Post subject: Re: Fuel pump and relay Reply with quote

hey

check the two vacuum lines at the back of the intake chamber. they can be broken due to them getting brittle over the years. they are connected to the fuel regulator and it is a possibility that this can be the issue. also, check all of your lines along the side of the chamber as well, for the two regulator valves and the vris. see if any vac lines got disconnected from those two pressure regulators.

do you have and error codes?

Green Machine (Green '97 ES) - 90K!
JDM chrome power-folding side mirrors with heated mirror retrofit/JDM chrome grill/JDM rear spoiler/Android 6.2" D-Din Navi/Four 7" Farenheit monitors/heated seat kit retrofits,1st and 2nd row/Crimestopper remote start

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chaseNYC
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New '98 and feelin' great
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Joined: 21 Jul 2003
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Location: Brooklyn, NY, USA, Planet Earth

PostPosted: Wed Feb 14, 2018 11:14 pm    Post subject: Re: Fuel pump and relay Reply with quote

when i turn the key to on, i cant remember hearing the click or not. in any event, the mpv does fire up so perhaps the clicking is happening but the sound from the relay is almost non-existent? i'll check mine out tomorrow for you.

swap the cap and rotor and see what happens. hopefully it just might be some vac lines that are disconnected or broken that you can replace.

here are the two vac lines attached to the fuel regulator boxed in red




hope this helps you

Green Machine (Green '97 ES) - 90K!
JDM chrome power-folding side mirrors with heated mirror retrofit/JDM chrome grill/JDM rear spoiler/Android 6.2" D-Din Navi/Four 7" Farenheit monitors/heated seat kit retrofits,1st and 2nd row/Crimestopper remote start

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chaseNYC
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New '98 and feelin' great
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Joined: 21 Jul 2003
Posts: 1768
Location: Brooklyn, NY, USA, Planet Earth

PostPosted: Wed Feb 14, 2018 11:24 pm    Post subject: Re: Fuel pump and relay Reply with quote

one last thing

Click here for my vac mapping post just in case.

Green Machine (Green '97 ES) - 90K!
JDM chrome power-folding side mirrors with heated mirror retrofit/JDM chrome grill/JDM rear spoiler/Android 6.2" D-Din Navi/Four 7" Farenheit monitors/heated seat kit retrofits,1st and 2nd row/Crimestopper remote start

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kidmoe
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PostPosted: Thu Feb 15, 2018 12:02 am    Post subject: Re: Fuel pump and relay Reply with quote

Thanks for the info! I will check out the vac lines tomorrow (assuming I'm not still sick) and I have the cap and rotor ordered and they will be here in a couple days. I have the access panel off to get to the fuel pump relay and I can actually put my hand on it while I turn the key. I can feel it click when I turn the key to the start position, but not if it's just in the on position. My biggest concern was that it wasn't priming. I'm used to hearing the fuel pump humming for a couple seconds, and thought I had a bad fuel pump before I investigated further and found out that it was pumping when I was turning the engine over. I'm a novice at all this, so any info on the workings of things is much appreciated. This car probably sat for some time after being impounded by a towing company. I was very hopeful that when I found the broken timing belt, that would be my only problem. I guess it will be another "learning experience".
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chaseNYC
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Joined: 21 Jul 2003
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Location: Brooklyn, NY, USA, Planet Earth

PostPosted: Thu Feb 15, 2018 9:05 am    Post subject: Re: Fuel pump and relay Reply with quote

is your check engine light on?

another thing you can do for about 20 bucks is to change your coolant temp sensor. if you are on your original sensor, it is possible that it could be bad. if you have a check engine light, check the codes first to see what you have. a bad coolant sensor can cause sputtering and bad idle.

Green Machine (Green '97 ES) - 90K!
JDM chrome power-folding side mirrors with heated mirror retrofit/JDM chrome grill/JDM rear spoiler/Android 6.2" D-Din Navi/Four 7" Farenheit monitors/heated seat kit retrofits,1st and 2nd row/Crimestopper remote start

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kidmoe
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PostPosted: Thu Feb 15, 2018 12:14 pm    Post subject: Re: Fuel pump and relay Reply with quote

I don't have access to a diagnostic tool at my house, so I haven't checked to see if there are any codes to read. The check engine light doesn't come on until the engine starts to misfire. If I replace the cap and rotor and there isn't significant improvement, I will start to investigate other options. I figure, even if everything would have worked out and it ran well after I replaced the broken timing belt, I still would have done a tuneup. So at this point I still haven't just started throwing parts at the problem. If the tuneup doesn't work, I'll put it on my trailer and take it to the parts store to have them read the codes. I'll keep you posted. Thanks again! Lots of good information here and I really appreciate all your suggestions.
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kidmoe
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PostPosted: Fri Mar 09, 2018 8:30 pm    Post subject: Re: Fuel pump and relay Reply with quote

Finally got a chance to get the MPV over to the auto parts store and had them check for codes. Came up with 3 codes. P0300 (multiple misfire), P1110 (Intake air temp Sensor), and P1345 (Camshaft position sensor).
I am starting to doubt myself and think that maybe I was off a tooth with the timing, even though I already double checked it. Would this cause the P1345 code if I did make an error when I replaced the timing belt?
I disconnected the crank position sensor just to inspect the connection. It all seemed fine and I reconnected the wiring and tried to start it again. It would just barely fire for a second and then quit. Before that I could start it and it would idle very rough, but would at least stay running.
I tried to test the crank position sensor with my multimeter, but I don't have a whole lot of confidence in the quality of the tool. I think tomorrow I will tear it down again and check the timing marks one last time just for my own peace of mind. Any other suggestions? Thanks!
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vincentkou98
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Joined: 10 Apr 2016
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Location: Walnut, California, United States of America

PostPosted: Fri Mar 09, 2018 9:10 pm    Post subject: Re: Fuel pump and relay Reply with quote

Double check the ignition timing as my friends MPV gave the same code for bad ignition timing.
1997 Mazda MPV 4WD 189K (Towing Package)
Black & Silver 2 Tone
1997 Mazda MPV 2WD 153K
Black & Silver 2 Tone
1996 Mazda MPV 2WD 260K (Parts Car)
White & Tan 2 Tone


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kidmoe
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PostPosted: Sat Mar 10, 2018 6:03 pm    Post subject: Re: Fuel pump and relay Reply with quote

It is a beautiful sunny day here for once so I had a chance to tear the whole thing down again and triple check the timing marks, and everything is lined up perfectly. It also gave me a chance to look around really well to see if there where any hoses or wires that where damaged or disconnected, but I found nothing. I'm going to keep tinkering and see what I can find. My timing light is a piece of junk, so I may have to invest in a new one, or see if my neighbor has one I can borrow. I'll keep you all posted.
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kidmoe
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PostPosted: Sat Mar 10, 2018 6:40 pm    Post subject: Re: Fuel pump and relay Reply with quote

Just went out and poked around under the hood a bit and started up the MPV. Still barely idles and misses a bunch. For some reason I decided to unplug the MAF and suddenly it started to idle much higher, but no sputtering. Seems to run on all cylinders fairly smoothly but cuts out when you give it gas (doesn't stall, just won't rev). Is this an indication that the MAF is bad or in need of cleaning? Or is this just another symptom that could be many different things?
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