I have 1998 Infiniti Q 45 with possible fuel pump issues

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waculjr903
Posts: 17
Joined: Wed May 14, 2014 6:36 pm
Car: 1998 Infiniti Q 45 base model w/132K all stock except K&N air filter, NGK Iridium Lazer cut plugs.
Location: Tyler,Tx 75758
Contact:

Post

Like I say I have 1998 Infiniti Q45 that In bought used a year ago. The only humming or buzzing I have heard is what sounded like the third break light buzzing a couple of times driving down the interstate. The car seems a bit sluggish at times, under acceleration. Yesterday, I got the oil changed with the usual Mobil- Synthetic. Two hours later, I drove 22 miles round trip to town. I drove about a mile to a stop sign, pushed on the gas midway, and the car stumbled once for about two seconds, then everything was fine. When I was a mile back from the house, I hit the gas down to the floor, and took off great, but acted like it was cutting out about three times, for about a second each. Is this the classic signs of needing to replace the fuel pump? And if this is the fuel pump, will I need to replace the fuel pump pressure control unit, that I have been reading about in other articles?


waculjr903
Posts: 17
Joined: Wed May 14, 2014 6:36 pm
Car: 1998 Infiniti Q 45 base model w/132K all stock except K&N air filter, NGK Iridium Lazer cut plugs.
Location: Tyler,Tx 75758
Contact:

Post

Also, if it is a fuel pump, what kind should I get? There are Airtex,Delphi, and two grades of Bosch, one with metal case for $212, and one with plastic housing, and filter screen with it for $$290. What else do I need to order? Besides pump, filter, o-ring?

3Q Jay
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Joined: Sat May 08, 2004 6:23 pm
Car: 94 Q45a
95 Q45a (sold)
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01 B15 Sentra (Daughter's)
Also Mine...
2010 A6 Avant
1977 F-150 (460!)
Location: Florida Coast

Post

when was the last time your fuel filter was changed? genuine nissan part or 'one size fits'?
what is the running measured fuel pressure and under load?
sounds like maf.

waculjr903
Posts: 17
Joined: Wed May 14, 2014 6:36 pm
Car: 1998 Infiniti Q 45 base model w/132K all stock except K&N air filter, NGK Iridium Lazer cut plugs.
Location: Tyler,Tx 75758
Contact:

Post

6mo. ago, and cleaned the mass airflow sensor while I was at it.

waculjr903
Posts: 17
Joined: Wed May 14, 2014 6:36 pm
Car: 1998 Infiniti Q 45 base model w/132K all stock except K&N air filter, NGK Iridium Lazer cut plugs.
Location: Tyler,Tx 75758
Contact:

Post

Also put a WIX fuel filter in.

waculjr903
Posts: 17
Joined: Wed May 14, 2014 6:36 pm
Car: 1998 Infiniti Q 45 base model w/132K all stock except K&N air filter, NGK Iridium Lazer cut plugs.
Location: Tyler,Tx 75758
Contact:

Post

Just put a fuel filter again, blew thru them both, no resistance difference in the two. I just got done running a tank of premium with a bottle of Lucas in it. When I put in fuse, turned the key to on, I did not hear anything. So I started the car, it fired right up! So would you think I would need a new fuel pump? I do not have anything to measure fuel pressure under load. What should I do?

3Q Jay
Posts: 2545
Joined: Sat May 08, 2004 6:23 pm
Car: 94 Q45a
95 Q45a (sold)
97 Q45t (sold)
01 B15 Sentra (Daughter's)
Also Mine...
2010 A6 Avant
1977 F-150 (460!)
Location: Florida Coast

Post

well, without maf voltage profiles and measured pressure, you are asking me to guess.
I'm going to GUESS that your fuel pump is fine.
FGY33 don't have the same fpcu issues that the early G50s do. i've never replaced an FGY33 fp. doesn't mean never happens.....

waculjr903
Posts: 17
Joined: Wed May 14, 2014 6:36 pm
Car: 1998 Infiniti Q 45 base model w/132K all stock except K&N air filter, NGK Iridium Lazer cut plugs.
Location: Tyler,Tx 75758
Contact:

Post

When you are speaking of MAF, do you mean Mass Airflow Sensor by the air box? Just asking to make sure... :gotme

3Q Jay
Posts: 2545
Joined: Sat May 08, 2004 6:23 pm
Car: 94 Q45a
95 Q45a (sold)
97 Q45t (sold)
01 B15 Sentra (Daughter's)
Also Mine...
2010 A6 Avant
1977 F-150 (460!)
Location: Florida Coast

Post

waculjr903 wrote:When you are speaking of MAF, do you mean Mass Airflow Sensor by the air box? Just asking to make sure... :gotme
yes.
it's also possible, even if you cleaned it, that your kn filter is coating the hot film element with oil.
Measured MAF output as a function of air flow (RPM) will tell us. must be linear, no dropouts.


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