The car stalled while driving on a side street. I pulled over to the curb and could not get it to run more than two or three seconds. I was towed home and the car sat for five months. I bought an airflow sensor (MAS) on ebay and installed it. It ran for about two seconds longer than before. The Ebay seller to told me he tested it on his car before putting it on the market. I had the car towed to a mechanic who said that his diagnostic machine read a faulty MAS, even though I had I told him about the one I bought. He then put the old one back in and used the plug that came with the new one. He did some work on it and then told me I should take it to a dealer. He had put the new MAS back and I was able to very carefully drive it home. If I gave it too much gas it would stall. The mechanic did not charge me. He said that since he didn't fix it, he wouldn't charge me. (That is rare)Since I couldn't afford to take it to a dealer, I decided to sell it. I listed the car on the Orange County Craig's List. A wonderful person from this site phoned me and made a few suggestions, which I tried, with out much difference in performance. He also told me about this site.He asked me about a sound from the fuel pump. I never heard anything from the fuel pump. He said that my be my problem. Then I started listening and once when I gave it a good boost I heard someone in the trunk gasping for air. (I am going to buy a fuel pump.) So, it drives, but it stalls and I don't drive it very far. It is in great shape, inside and out. I hate to sell it. Any advice?
Modified by parsecsam at 4:33 PM 3/9/2008
1990 Infiniti Q45 stalls when acelerated.
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elwesso
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Re: 1990 Infiniti Q45 only 112,800 miles - stalls when acelerated (parsecsam)
Iwould definitely check fuel pressure.. fuel pumps are very common to go out on Qs so it wouldnt surprise me in the least.. Always suspect a fuel pump unless you have records of its replacement.
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maxnix
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1995 Infiniti Q45t
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Re: 1990 Infiniti Q45 only 112,800 miles - stalls when acelerated (parsecsam)
And suspect the FPCU also if you have run for a while with this type of behavior.
If you had posted a maintenance history summary, we might have pointed you somewhere else.
Hope you have read the timing chain guide article.
If you buy the pump, don't forget the O ring and inspect the tank carefully. Steam clean if any evidence of contamination.
If you had posted a maintenance history summary, we might have pointed you somewhere else.
Hope you have read the timing chain guide article.
If you buy the pump, don't forget the O ring and inspect the tank carefully. Steam clean if any evidence of contamination.
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Q45tech
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- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: 1990 Infiniti Q45 only 112,800 miles - stalls when acelerated (maxnix)
Bad solder joint in FPCU caused by bad fuel pump running slow drawing excess current melting and remelting solder pad . The trimode FPCU may have already failed [transistor poped] from high current in the high flow section [acceleration].
Common so very common.
Common so very common.
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goody90q45
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Re: 1990 Infiniti Q45 only 112,800 miles - stalls when acelerated (parsecsam)
Welcome to NICO Sam. I'm the guy that called you yesterday and suggested that you join and post up your issues in this forum. After reading your Craigslist ad and your blog I knew that the problem with your Q was something very simple and not worth letting it go at such a low price. Besides that, the Q is much more of a babe magnet for a spry 80 year old than an old beater truck.
From talking to you on the phone you told me that other than the MAF code from your ECU you're not having the typical MAF problems which would be rising/falling RPMS, stalling, and upon restart driving away like nothing ever happened. Even after changing the MAF and pigtail you said you had the same symptoms and no CEL (check engine light). It would be nice to know what codes are stored in the ECU now. Could there really be a problem wit the MAF or is it the pigtail that was wired in?
Your description leads me, and everyone else who's posted so far, to have you check the fuel delivery system- fuel pressure, fuel pump, fuel pump contol unit (FPCU), and fuel filter. Your Q is at about 120k miles and that's just about when all Q's will need at least a new fuel pump. Don't go throw $$ at parts though until you've done a few simple checks. Start with a known good fuel filter. Do you know when the last time yours was changed?
Wes's (elwesso) suggestion to check fuel pressure would be a good start. This is done by installing an in-line pressure gauge on the outlet line from the fuel filter to the injector rail. The fuel filter is on the passenger side below the fuse box. Your mechanic should have this setup in his bag of tools. Crank the engine and you should read in the 40psi range. If you can keep the engine running and raise the rpm it should maintain pressure.
Brian and Tech have you looking at the individual components of the fuel system which is something you may be able to do today while you wait to get in to see your mechanic. Start by examing the connector on the FPCU. Remove just a couple of the top fasteners on the rear trunk trim and you'll be able to reach in and unplug the FPCU. You can see it in the background in the pic mounted under the rear deck. Is there any sign of burnt pins in the FPCU or the connector?
The FPCU should be replaced when the fuel pump goes bad and if the previous owner did one and not the other you may have inherited their problem. The pic shows the FPCU unplugged. By installing a jumper from the pin shown to ground, the fuel pump will be grounded out to run on high speed only. If your Q runs like a bat out of hell with the pump grounded then the problem is a fried FPCU.
Finally, listen to the fuel pump with the car idling. Do you hear what sounds like a swarm of bees in the trunk? You could have a bad fuel pump and a bad FPCU.
Do these couple of checks and you should have a pretty good idea of what the fuel delivery system is doing. Let us know how it turns out.
From talking to you on the phone you told me that other than the MAF code from your ECU you're not having the typical MAF problems which would be rising/falling RPMS, stalling, and upon restart driving away like nothing ever happened. Even after changing the MAF and pigtail you said you had the same symptoms and no CEL (check engine light). It would be nice to know what codes are stored in the ECU now. Could there really be a problem wit the MAF or is it the pigtail that was wired in?
Your description leads me, and everyone else who's posted so far, to have you check the fuel delivery system- fuel pressure, fuel pump, fuel pump contol unit (FPCU), and fuel filter. Your Q is at about 120k miles and that's just about when all Q's will need at least a new fuel pump. Don't go throw $$ at parts though until you've done a few simple checks. Start with a known good fuel filter. Do you know when the last time yours was changed?
Wes's (elwesso) suggestion to check fuel pressure would be a good start. This is done by installing an in-line pressure gauge on the outlet line from the fuel filter to the injector rail. The fuel filter is on the passenger side below the fuse box. Your mechanic should have this setup in his bag of tools. Crank the engine and you should read in the 40psi range. If you can keep the engine running and raise the rpm it should maintain pressure.
Brian and Tech have you looking at the individual components of the fuel system which is something you may be able to do today while you wait to get in to see your mechanic. Start by examing the connector on the FPCU. Remove just a couple of the top fasteners on the rear trunk trim and you'll be able to reach in and unplug the FPCU. You can see it in the background in the pic mounted under the rear deck. Is there any sign of burnt pins in the FPCU or the connector?
The FPCU should be replaced when the fuel pump goes bad and if the previous owner did one and not the other you may have inherited their problem. The pic shows the FPCU unplugged. By installing a jumper from the pin shown to ground, the fuel pump will be grounded out to run on high speed only. If your Q runs like a bat out of hell with the pump grounded then the problem is a fried FPCU.
Finally, listen to the fuel pump with the car idling. Do you hear what sounds like a swarm of bees in the trunk? You could have a bad fuel pump and a bad FPCU.
Do these couple of checks and you should have a pretty good idea of what the fuel delivery system is doing. Let us know how it turns out.
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Haitian_King
- Posts: 2868
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- Car: 1992 Black Infiniti Q45 /w TCS
1995 Black Infiniti Q45 - Location: South NJ/PA/Canada
Re: 1990 Infiniti Q45 only 112,800 miles - stalls when acelerated (goody94q45)
Did not see this when I replied to his post in the Summer Gas thread.
Sam's reply
3/9/08 THANK YOU FOR YOUR RESPONSE. I checked the FPCU pins and they look clean. I wasn't sure where to ground the pin, and wasn't sure if I should plug it in or leave it out. Do I ground the the unit or the plug? I noticed that there was another connector that was disconnected below the FPCU (Have photos. If I can figure out how to post them I will - I did post them on my site. You can get to it by a google search [parsec infiniti frame]. I could not connect it because someone had folded the long end and wired it. I don't know what it is about, but it is not plugged in. If I knew what it was, I might plug it in.Again, Thanks everyone for your support. If you go to my site you will see the Q45.
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maxnix
- Posts: 22627
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1995 Infiniti Q45t
2000 Infiniti Q45
Re: Sam's reply (parsecsam)
You have to eck the board itself as the resistor can fail without burning the plug. Search on Tangalora fuel pump in IOM.