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Are you waiting long to crank the motor after building pressure? If you build pressure and then it drops to 20psi within ~5-10 seconds you're probably draining it to the tank. This usually happens when the FPR is bad or the pulsator at the pump. There's an FSM page or two for that problem, but it's essentially just clamping off the supply and return fuel lines just outside the fuel sending unit at the tank. If pressure holds when you clamp the return line, then it's the FPR. If it holds when you clamp the supply line, it's probably the pulsator. That's _likely_ an entirely separate issue and may not mean much.
I know it was probably a pain getting to that 4-way connector at the distributor - but would you mind trying the fuel pressure test with it unplugged and the car warmed up? At that point the cold start injector shouldn't be dumping fuel at all and the pressure shouldn't drop.
I wait a little bit to see what the pressure does. It starts dropping almost immediately. Yea, draining to the tank does sound likely. I just replaced the FPR and checked it for fuel leakage...and the psi does go up when I remove the vacuum line. Is the "pulsator" part of the fuel pump? I replaced that within the last few hundred miles as well, but will try this test too.
Thanks for outlining that. What do I use to clamp it? Just some vice grips or something like that?
Thanks!
HELL NO!!! The proper tool is THIS but basically, you don't want too much pressure so don't get carried away. Jaws should be flat and not points.
Problem is the jagged edges that can hurt the hose and too many people think this is a "HE MAN" contest and crank on it hard. Flat jaws and low enough pressure, maybe.
HELL NO!!! The proper tool is THIS but basically, you don't want too much pressure so don't get carried away. Jaws should be flat and not points.
Problem is the jagged edges that can hurt the hose and too many people think this is a "HE MAN" contest and crank on it hard. Flat jaws and low enough pressure, maybe.
Glad I asked. I was kinda worried about chewing up the hose with the teeth on vice grips. Thought of those...have seen them before and figured they were useful...here's another excude to get 'em I guess. Thanks!
Are you waiting long to crank the motor after building pressure? If you build pressure and then it drops to 20psi within ~5-10 seconds you're probably draining it to the tank. This usually happens when the FPR is bad or the pulsator at the pump. There's an FSM page or two for that problem, but it's essentially just clamping off the supply and return fuel lines just outside the fuel sending unit at the tank. If pressure holds when you clamp the return line, then it's the FPR. If it holds when you clamp the supply line, it's probably the pulsator. That's _likely_ an entirely separate issue and may not mean much.
I know it was probably a pain getting to that 4-way connector at the distributor - but would you mind trying the fuel pressure test with it unplugged and the car warmed up? At that point the cold start injector shouldn't be dumping fuel at all and the pressure shouldn't drop.
Can you tell me where to find that in t FSM, or any other sections related to hard starting? My PC is nearing the end of it's service life, and I can't scroll through the FSM very well...just if you know offhand. Thanks!
First off, I tried that 9th injector test. Hope I did it right. I put one probe in one of the pins, and the other probe to the intake manifold. I got .6 ohms on one, and 7.8 ohms on the other. Not sure if that tells you anything itself, but I went further. When cranked, I got 9.59 volts.
I tried starting it with the pedal floored, but it doesn't start any easier.
I sat there and thought about how the pressure goes to 43, and drops down to 20 so fast. Now, I tend to put my key in, wait to hear the fuel pump, and then start it. I decided to try and just put the key in and crank it wihtout my usual, customary wait, and it does start faster that way.
I guess my next step is to get some pinch pliers, and try that fuel line test, but like to hear anything anyone has to suggest in the meantime.
change the fuel pump relay.
You're probably building enough oil pressure to energize the oil pressure fuel pump switch and that's what's turning on your pump
Following up here. You're talking about one of the two relays behind the battery, right? I replaced them a few hundred miles ago, but replaced them again, along with the sockets and harnesses, but unfortunately it didn't help. Still hard to start. I thank you for the suggestion though.
Cold start switch and cold start relay are the same, I should have called it the cold start switch. Pull of the cold start injector connector and make sure one of the pins is grounded by using the ohm setting on the multi meter. Touch one of the connector pins and the intake manifold and see if it reads around 1 ohm, then touch the other pin and see what it reads, it should be open no reading. The pin that reads open should then read 10-12 V (switch the multi meter to read DC volts) when you crank the car. This will determine if you are getting power to the cold start injector when you crank the car.
The fuel pressure dropping to 20 PSI in one minute is not the issue unless you are getting a flooding condition when the car is warm. If you are getting 42 PSI at cranking you have fuel present and that is removed from the equation.
Sorry if I am repeating myself...just going over this stuff again to see if I missed anything...
I tried that 9th injector test. Hope I did it right. I put one probe in one of the pins, and the other probe to the intake manifold. I got .6 ohms on one, and 7.8 ohms on the other. Not sure if that tells you anything itself, but I went further. When cranked, I got 9.59 volts.
I tried starting it with the pedal floored, but it doesn't start any easier.
I sat there and thought about how the pressure goes to 43, and drops down to 20 so fast. Now, I tend to put my key in, wait to hear the fuel pump, and then start it. I decided to try and just put the key in and crank it without my usual, customary wait, and it does start faster that way.
If the car starts easier hot I assume the reason for the hard starting is lack of fuel. To confirm this what happens if you put the peddle all the way to the floor and try to start the car (release as soon as the car starts)? This should turn off the injectors and if it was a lack of fuel the car should not start. If the car starts very quickly and clears out immediately it was too much fuel and that will cause us to go down a different path.
I tried the pedal to the floor, and it's not any easier to start. Thanks!
I sat there and thought about how the pressure goes to 43, and drops down to 20 so fast. Now, I tend to put my key in, wait to hear the fuel pump, and then start it. I decided to try and just put the key in and crank it without my usual, customary wait, and it does start faster that way.
Thanks!
Why the customary wait? If you had looked, you'd see that the pressure gets up to spec within a second or less so waiting is unnecessary. If it starts faster WITHOUT the wait, maybe there is a fuel leak which explains why it drops fast. That leak could be external (which you say it doesn't) or internal and goes back to the tank. Do the clamping of hoses to test or we can keep throwing parts at it.
Why the customary wait? If you had looked, you'd see that the pressure gets up to spec within a second or less so waiting is unnecessary. If it starts faster WITHOUT the wait, maybe there is a fuel leak which explains why it drops fast. That leak could be external (which you say it doesn't) or internal and goes back to the tank. Do the clamping of hoses to test or we can keep throwing parts at it.
I guess I just got used to giving it a sec, before I turned the key. Just habit, I suppose. Done that with every car I've had when I can hear the pump, and it's never been a problem.
What would cause an "internal" leak...any idea where to start looking?
Unfortunately, I keep very odd hours, but I can do those tests later this morning. Will have to get those pliers first though. Will the one concerning the pulsator tell me anything if mine has the bypass hose? Been a few years, but I think mine has that bypass hose. Thank you.
Last edited by racerseks; Jun 11, 2017 at 01:29 AM.
Why the customary wait? If you had looked, you'd see that the pressure gets up to spec within a second or less so waiting is unnecessary. If it starts faster WITHOUT the wait, maybe there is a fuel leak which explains why it drops fast. That leak could be external (which you say it doesn't) or internal and goes back to the tank. Do the clamping of hoses to test or we can keep throwing parts at it.
I might be able to do the first part of that test in a little bit, since I won't need someone to watch the gauge...but for the second one, will it tell me anything if I don't have a pulsator, and have the bypass hose instead?
Is this testing in the Factory Service Manual? If so, do you know what section it's in?
I guess I just got used to giving it a sec, before I turned the key. Just habit, I suppose. Done that with every car I've had when I can hear the pump, and it's never been a problem.
What would cause an "internal" leak...any idea where to start looking?
Unfortunately, I keep very odd hours, but I can do those tests later this morning. Will have to get those pliers first though. Will the one concerning the pulsator tell me anything if mine has the bypass hose? Been a few years, but I think mine has that bypass hose. Thank you.
Not sure why. I saw my adopted dad always do that. Shut AC off when the car is being shut down, let it run for a few before he turns it on. I never was able to teach him about the "set it and forget it" paradigm. Yes, it won't be a problem because your fuel system is supposed to be able to hold the prime for a bit. Also, I imagine that is why you can't turn the key off quickly and turn it on and have it re-prime.
Who knows. Could be a bad FPR (they can and do come out leaking out of the box) since they are only a rubber membrane at best. Could be that the injectors are leaking although the car will seem to run fine because the ECM can compensate. Could be that the pulsator or the hose replacing the pulsator is leaking. Could be that the pump is not holding the pressure. Hard to say.
Hard to say until we look at it. You'd have to take the pump out and see if there is a rubber hose between the pump and the metal tube or whether there is a pulsator. If there is a hose, it could leak just because it does or because it has the wrong type of hose.
Not sure why. I saw my adopted dad always do that. Shut AC off when the car is being shut down, let it run for a few before he turns it on. I never was able to teach him about the "set it and forget it" paradigm. Yes, it won't be a problem because your fuel system is supposed to be able to hold the prime for a bit. Also, I imagine that is why you can't turn the key off quickly and turn it on and have it re-prime.
Who knows. Could be a bad FPR (they can and do come out leaking out of the box) since they are only a rubber membrane at best. Could be that the injectors are leaking although the car will seem to run fine because the ECM can compensate. Could be that the pulsator or the hose replacing the pulsator is leaking. Could be that the pump is not holding the pressure. Hard to say.
Hard to say until we look at it. You'd have to take the pump out and see if there is a rubber hose between the pump and the metal tube or whether there is a pulsator. If there is a hose, it could leak just because it does or because it has the wrong type of hose.
My son! LoL...Well, I'll say this. My Dad did that same AC ritual, so I guess that's where I get it from...'cause I do it too! LoL! He was born in 1925, so I guess that's just how they did stuff back then.
Well, I had my other set of eyes around this morning. Did the "pinch" tests, and going to bed soon..."odd hours", ya know?
When clamping the return line, the pressure went to about 43psi or so, and I'd clamp it. From there, I don't know if it was a slight delay in clamping, but it held just under 38 psi for 20 minutes. When I clamped the send line, it went up to 43 as well...but dropped very fast. So does that mean my FPR is probably okay, and most likely it is something in the tank, such as pulsator or bypass hose, fuel pump, or check valve? Also, is the check valve part of the fuel pump...or is it a separate part?
While in there, I replaced the "vent" hose. Big rip in it...but that happens when this stuff comes on and off over and over again. Between two or three fuel pump changes, pumping "bad" gas out of it, etc. etc. over the last few years, I've probably had all that off half a dozen times or so now...maybe more.
Anyway, if that looks like what's going on here, I'll pull the pump out in the next few days pending rain here in Florida, and replace it and the bypass hose and/or pulsator if need be. I am almost positive I have the bypass hose in there from a previous fuel pump change. Think I'll go with a better one this time.
Not sure why. I saw my adopted dad always do that. Shut AC off when the car is being shut down, let it run for a few before he turns it on. I never was able to teach him about the "set it and forget it" paradigm. Yes, it won't be a problem because your fuel system is supposed to be able to hold the prime for a bit. Also, I imagine that is why you can't turn the key off quickly and turn it on and have it re-prime.
Who knows. Could be a bad FPR (they can and do come out leaking out of the box) since they are only a rubber membrane at best. Could be that the injectors are leaking although the car will seem to run fine because the ECM can compensate. Could be that the pulsator or the hose replacing the pulsator is leaking. Could be that the pump is not holding the pressure. Hard to say.
Hard to say until we look at it. You'd have to take the pump out and see if there is a rubber hose between the pump and the metal tube or whether there is a pulsator. If there is a hose, it could leak just because it does or because it has the wrong type of hose.
Well, I got the fuel pump out of there the other day. It does have the hose instead of the pulsator. Nothing written on it, but it looks brand new and hasn't degraded at all. Clamps are on good and tight too.
Any way to test the check valve on the fuel pump, ort anything else? Any next step?
Well, I got the fuel pump out of there the other day. It does have the hose instead of the pulsator. Nothing written on it, but it looks brand new and hasn't degraded at all. Clamps are on good and tight too.
Any way to test the check valve on the fuel pump, ort anything else? Any next step?
Thanks...
Outstanding. Now we know it isn't leaking from the pulsator. As mentioned, if the return line is clamped and it does not hold pressure, it has to go somewhere. So, either the pump or the injectors are leaking or the FPR is. If the FPR is leaking, you can see it in the manifold. Take that out of the equation and we have the injectors. Without a bench, we cannot really test it. So we will circle jerk back to that later.
Now we need a couple of people involved. The guy at the pump will give the signal and the guy in the car turns the key and read the hose. A second later (The priming should be about done), clamp off the feed hose. If the pressure drops, it is between the regulator and the clamp. If it holds, your pump is an issue.
Maybe I missed it but did you ever put the old injectors back in and see if it started easier?
bingo, as mentioned 90 posts ago the problem is not the fuel pressure drop. If you have pressure when you crank the car the pressure drop is a non issue. Most likely the chip needs to be adjusted to the new injectors, or the cold start injector has failed.
