1990 q45 cranks but does not start

[saps5789]

I have a 1990 q45 that runs good most of the time.Sometimes out of nowhere I will get in car and it will crank over but will not start.The only way to get it to start is to pull the fuel pump fuse from the fuse box then crank car and it will start.I then have to put fuse back in and pump gas pedal to keep running.After about 5 sec everything clears up and it runs fine.Anyone have any sugestions.

[Infinitiguy19]

I would have to say that it is flooded, Meaning you have a leaky O-ring or possibly even an open injector, Most likely one or more of your injectors is bad though.

Follow this to test your injectors: http://q45.org/ohminjectors.html

Have you read about the chain guides? zerothread?id=25201

Good luck and Welcome to NICO.

[maxnix]

Anyone have any sugestions.

Read your OM on how to start when it is flooded.

[Infinitiguy19]

Sorry I should have mentioned that by holding the accelerator to the floor with the key in the on position usually does the trick.

[goody90q45]

I would have to say that it is flooded, Meaning you have a leaky O-ring or possibly even an open injector, Most likely one or more of your injectors is bad though.

I agree with Paul- Probably a dead injector or leaking o-ring. How's your gas mileage? Check engine light on? Replaced the fuel pump or fuel pump controller? Mileage on your Q? White smoke coming out he tailpipe at startup?

[saps5789]

Thanks for everybodys help.I tested the injectors 7 of them were between 10-14 and 1 was 17.5.I am only getting about 10 mpg.The car has 107,000.I have changed the fuel pump and control box about 1 year ago with used ones.It only happens like 3 times a week when the car is warm and has been sitting about 1 hour.it never happens in the morning.I do smell gas once in awhile if car is idling.I did change a injector last year when car had no power from 0 to 30mph.that seemed to fix that problem.I tried holding the gas pedal to the floor and it still does not start.the only way to start is to pull fuse.I have anouther question when i pull plug from fuel control box the car starts is this normal.

[Infinitiguy19]

Are you talking about the fuel pump control unit that is the computer in the trunk that usually goes bad when you wait to replace the fuel pump? If so NO

When starting or under WOT AKA Wide Open Throttle the fuel pressure is 43.3 PSI when cruising the fuel pressure is 34 PSI.

I would replace soon because so you can further reduce your risk of hydro locking.

Is the car running really rough, like on 7 cylinders?

Which one was bad? was it 1,2 or 8 if so then those are replaceable without removing the plenum.

Good Luck.

[saps5789]

The one reading of 17.5 was the number 3 injector.is 17.5 bad enough to change.the car seems to be running fine.It does not seem like it is running on 7 cyl.It has plenty of power although from what i have been reading about these cars from this web site since i own the car (about 2 yrs) I have always thought I have been lacking power because it has never responded well from 0 to 30 although it has been better since i changed the 1 injector.How can the car start when I pull the plug from the fuel control box(yes the one in the trunk).What is hydro lockingThanks

[Infinitiguy19]

OK the reason your 0-30 suck is because the 1990-1992 Q45's start out in 2nd gear the only way to make it start out in 1st gear is to punch it below 30 MPH or manually put it in 1st gear.

I have a 1st gear start computer from a 1994 Q45, it will start in first gear for more power but its recommended you find a 1993 Q45 first gear start TCU AKA transmission Control Unit. I can give it to you for $55 shipped

Also read this on prolonging your A/T: zerothread?id=103519

Read this on adding a external transmission cooler which is highly recommended: http://q45.org/trannycooler.html

I am not exactly sure why it starts because I can't be there to diagnose your car.

17.5 means a dead injector, anything above 14 is bad. try a BG fuel system flush to see if that changes anything.

Hydro lock: http://en.wikipedia.org/wiki/Hydrolock

[saps5789]

Thanks for info about starting in 2nd gear.now i know why i never had power off the line.If my 1 injector is bad I am still not sure why car starts most of the time and doesnt start sometimes when warm.Just because it is reading 17.5 doesnt mean it is leaking.How do i determine if i have a leaking injector or if it has something to do with the pump or control box.Why does it start when i pull the fuse of the pump.The only thing that has changed is gas milage it went from about 13 to 10.

[maxnix]

10-13 indicates a lot of warm up and idling time or a lot of deferred maintenance.

Read the sticky at the top and report back, please.

[saps5789]

10-13 what do u mean.I did an ohms test on injectors and they all came out between 10-14 except 1 which read 17.5.How do u find a leaky injector if that is whats causing car not to start(when its warm)Once again can anybody explain why car would start with plug out of fuel contrl box.Why does it only start when i pull fuse that operates fuel pump.

I dont know where to startI tried doing a manual shift starting in first.What a difference.I never felt that power starting in drive.Thats another reason i dont think i have a dead injector it is running very smooth & powerful.

[96Qowner]

It sounds to me like you have a leaky lower O-ring on an injector. When you pull the pump fuse or disconnect the FPCU, the pump doesn't run and doesn't deliver any fuel into the cylinders. If you have an O-ring leak, if the pump is running, it'll dump fuel into a cylinder when you first turn the key, flooding it. When you disable the pump, the car will start and run very rich.

But if it's only one cylinder, you'd think the car would start anyway. Any smell of gas when it won't start? Does this happen when the car has been sitting or after it's been off for only a few minutes? If it's a lower O-ring, you HAVE to deal with that ASAP. You run the danger of hydrolocking the motor with a full cylinder of fuel and bending a rod when you try to start it.

Both unplugging the FPCU and pulling the pump fuse accomplish the same thing - it disables the fuel pump. But holding the pedal to the floor before you turn the key should accomplish the same thing.

[saps5789]

Thanks for the reply,How do i find out which injector is leaking.I do smell gas when this happens.I never tried putting pedal to floor before i turn ignition.when i disconnect fpcu why does the car still start.I still here the fuel pump running also.It only happens after car sits form 15 min to about 2 hours.always starts when cold.

[Infinitiguy19]

No easy way to tell unless it was 1,2 or 8, Usually we Q45 owners just pull the plenum to check.

[96Qowner]

Thanks for the reply,How do i find out which injector is leaking.I do smell gas when this happens.I never tried putting pedal to floor before i turn ignition.when i disconnect fpcu why does the car still start.I still here the fuel pump running also.It only happens after car sits form 15 min to about 2 hours.always starts when cold.

With the FPCU disconnected, the pump won't run - can't be what you're hearing.

Also, the fuel rail remains pressurized when you turn off the car - it then continues to dump fuel past the leaky O-ring until the pressure is gone. After a couple hours, the fuel drains away into your oil, and you can start the car normally.

Check the condition of your oil. I bet it's full of gasoline. That'll be confirmation that it's a bad O-ring. If you can hook a Consult up to it, you may be able to determine which cylinder it is.