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Won't start without starting fluid?


DSMNerd6889
12-10-2007, 08:45 AM
Hey guys, I've been fighting with my buddy's 90 gsx for a while now... we've finally gotten it started, but it seems it'll only start when you use starting fluid. Do you guys have any idea why this may be? Thanks in advance.

david-b
12-10-2007, 10:05 AM
Sounds like not enough fuel is getting there. Any leaks in the fuel lines? FP ok? Fuel Filter old?

DSMNerd6889
12-10-2007, 01:05 PM
I don't know of any leaks... the fuel pump is supposed to be a newer walboro pump, but I haven't checked it out. There is a fuel pressure gauge... what should it be reading?

JoeShmoe
12-10-2007, 01:11 PM
Check the pump itself, my money is on that.

SilvrEclipse
12-10-2007, 01:21 PM
You gauge should be reading about 42psi I think.

david-b
12-10-2007, 01:47 PM
42psi is stock fuel pressure. When I installed my gauge, I had a leak. When the car sat overnight, it would drain the fuel lines from the filter to the rail, causing a hard start up, which sounds like you have. BUT, if it doesn't start at all, sounds like it's deeper. Find the pressure sensor and check for leaks. The Fuel pump may also not have been installed properly

gthompson97
12-10-2007, 02:05 PM
Fuel pressure should be 36-38 at idle. If the pressure drops slowly after you turn off the engine, you've got a leaky injector or a leak somewhere else. If it drops immediately after turn off, the fuel pump is bad. When was the last time the car was tuned up?

SilvrEclipse
12-10-2007, 02:12 PM
As soon as my pump turns off the pressure drop pretty quick. I think I remember hearing that the walbro pumps dont have a check valve or something to hold the pressure like the stock pump does. And Im positive I have no leaks

david-b
12-10-2007, 02:25 PM
Since when was it 36-38? Mine sits at 42.

Oh, GSX. Got ya.

gthompson97
12-10-2007, 02:43 PM
420a is 42psi, 4g63T is 36-38.

SilvrEclipse
12-10-2007, 03:11 PM
techniacally...

95 420a - Has an adjustable fpr, 42psi full vac. 48-50psi 0 vac.
96+ 420a - 48psi

nofear39427
12-10-2007, 06:52 PM
There are a couple of things that it could be.
1.Fuel pump is losing prime(odd for it being new)
2.Fuel Filter is stopped up and wont allow gas through
3.Not getting proper spark so check the plugs and wires<<I have had this prob before)
Any check engine lights btw?

DSMNerd6889
12-15-2007, 10:16 AM
Okay guys... I swapped out fuel pumps with another that I knew worked... and we primed it up and got it to run, and after sitting overnight, the fpr gauge is now reading zero... So I'm guessing that I am losing fuel somewhere. There are no visible leaks, I'm trying to think of where I may be leaking. Would a bad injector ring cause this problem? Thanks for all the help again!

SilvrEclipse
12-15-2007, 10:23 AM
Your not going to hold fuel pressure over night. My car will sit for 5 min and lose all the fuel pressure. The fuel pump should cut on as soon as you turn the key and it only takes it a second to prime. You may still have a leak though if your having trouble starting the car.

A bad injector o ring wont loose your prime bc the injectors will be closed. It will leak fuel all over your motor. No good

DSMNerd6889
12-15-2007, 10:57 AM
Hmm, I was under the impression that the fuel line was always pressurized... the fuel pump won't turn on unless the ignition is on and your cranking the motor, so you always have to start dry like that?

SilvrEclipse
12-15-2007, 11:06 AM
My car actually primes the pump when you turn the key on. I think some turbo model cars did this and others did not.

Your fuel line is not going to hold pressure unless the pump is on. I think the stock pump may have been able to hold a little bit but the aftermarket pumps wont hold any.

Like I said it only take a second to pressurize the lines when the pump turns on so I dont think that is your problem. So the car as of now wont crank? Hw much pressure are you getting while cranking?

DSMNerd6889
12-15-2007, 11:16 AM
I think that it may be a 1g/2g difference... If I recall correctly, my 95 Talon primed in accessory mode... but the manual says it has to be cranking for this 1g.

SilvrEclipse
12-15-2007, 11:20 AM
So after you primed the fuel line the car ran fine? Did you drive it around or let it idle? When you cut it off would it crank right back up?

david-b
12-15-2007, 01:28 PM
For reference the 420a (not sure what else, most cars should do this also) "primes" or pressurizes when key is turned all the way on before the engine gets cranked. It's still technically under pressure due to the fact that there is no place for it to go. The injectors are closed, the pump is off, and the lines are still full of fuel. You obviously want the pump to turn on and to pressurize the system before the motor starts cranking or it'll take even longer to start.

Just to clear that up.

DSMNerd6889
12-15-2007, 01:38 PM
After I prime it and use ignitor fluid, the car will start and run and we can drive it around.... if we turn it off and then try to start it back up, it'll start, but it starts kinda hard... Dave... my question is this... since my fpr gauge is dropping to 0 after it's set for a while... where would you suppose the fuel is going? I was thinking it was flowing back into the tank due to a faulty fuel pump, but that doesn't seem to be the case. I'm going to change the fuel filter for shits and giggles. Other than that, I really have no clue at this point.

SilvrEclipse
12-15-2007, 02:11 PM
The fuel goes back into the tank. I believe the pumps have some sort of check valve in them but the pressure is still going to leak out.

DSMNerd6889
12-15-2007, 02:14 PM
I don't understand that last post at all.... the fuel goes back into the tank.... but there is a check valve so that the fuel won't go back in the tank? I'm very confused.

SilvrEclipse
12-16-2007, 04:26 PM
There is sort of a check valve system I THINK, but the pressure still leaks out. Its not suppose to stop it completely.

david-b
12-16-2007, 06:00 PM
If the fuel pumped back into the tank after shut off, when you go and disconnect a fuel line even after the car has been sitting for a long time, there would be no fuel in the lines then. Not the case. Before you touch the fuel system (ie fuel filter change) you have to depressurize the fuel system by opening the gas cap, disconnecting the fuel pump, and starting the car numerous times. This works out all the pressure in the lines then and makes it accessible.

If all the fuel went back in the tank after shutoff, this whole process would be unnecessary.

So the gauge reads 0psi after a while or how is that working? Did you check the gas cap and see if it actually tight or leaking at all? It seems like there's something causing you to lose pressure, like maybe it is going back in the tank then, especially if there's no puddles or leaks right?

DSMNerd6889
12-16-2007, 09:11 PM
Well.... I halfway don't want to post this because it makes me look like a retard, but since you guys helped so much, I feel that you deserve some resolution. The fp gauge is still bleeding back to zero, but that may be because I don't have the fuel pump completely back on (air tight with sealant), but the car now starts still. The problem was that my ignition timing was way off... I mean WAY off. There you have it... perfectly good running dsm (unheard of) > idiot mechanic.

SilvrEclipse
12-16-2007, 11:59 PM
Glad you got it running, thats all that matters.

SilvrEclipse
12-17-2007, 12:00 AM
If the fuel pumped back into the tank after shut off, when you go and disconnect a fuel line even after the car has been sitting for a long time, there would be no fuel in the lines then. Not the case.

To answer daves questions. Fuel will remain in the lines because its not getting sucked out. But its not under pressure, when you disconnect your fuel line does the fuel spray out? It will leak because there is still fuel sitting in the lines, its just not under pressure.

DSMNerd6889
12-17-2007, 09:24 AM
There are no words to express how frustrated I am right now... we let the car sit over night and now it won't start again... I love dsm's so much.

DSMNerd6889
12-17-2007, 04:05 PM
Okay... I think I found the problem... the injectors are firing in the order of 1-2-3-4... the firing order should be 1-3-4-2. The injectors and ignition should be synched right? It looks like someone may have done a little rewiring to the injectors, should I hook them up so they squirt 1-3-4-2 like the firing order?

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