Why the"*&#@ won't my car start???

[Bob Avellar]

Here's the scenario:
Car starts fine if I start it every day.
Car many times will not start after sitting through the weekend.
When it does not start it does have spark to the plugs.
Injectors are being pulsed as I have checked them with a light designed for the injector harness.
Fuel pressure gauge reads normal (45psi).
Car cranks but it makes no inkling of firing. Just cranks and cranks.
Mat sensor reads actual temp.
Water temp sensor reads actual temp.
I see the Cam sensor turning (must if the injectors are pulsing anyway, right?)
And the crank signal must be there if I have spark.
I am using a MAF T+ now but the problem was there before I made the change. It made no difference.
The ONLY known problem I have with the car is the check valve or maybe something wrong with the intank connnection to the fuel pump. I have done tests to determine why my fuel pressure only holds for about 20 minutes and pinching the FEED line near the tank is the only thing that helped to maintain pressure for any length of time. Actually it held only slightly longer and then it started going down as usual. When I release the pinched feed line the pressure drops 10 psi instantly.
OK, so everyone will tell me to drop the tank and fix or change the pump. I have a new one here ready to go in except I just put more gas in the tank the other day. Maybe that will solve everything but- I read normal pressure on the gauge (which I know to be dead on acurate. Can I be reading AIR pressure in the fuel line instead of actual fuel????
If I squirt some ether into the alky nozzle the motor tries to start. Usually after that it sometimes will start. Plugs don't get wet.
I have all new braided fuel lines, brand new filter (in the correct direction). It just doesn't make any sense to me at all and it's driving me nuts. Like I said maybe the new pump will cure everything but I can't understand it not starting with pressure at the end of the fuel rail and everything else normal. Car must get mad at me if I don't pay attention to it on a daily basis.
T+ does have security mode but when that is working the car will run for a few seconds-and the problem existed before i switched to the T+ anyway.
Any thoughts or ideas what else could possibly cause this problem or how I can have fuel pressure with no fuel even with pulsing injectors? Sounds like I'm asking for an aswer to a problem that can't happen-but that's why I'm so aggravated.

 

[zam70]

well, You've kind of answered your own question...

fuel pump.
There are 2 parts to fuel
1) pressure
2) volume

you've got to have both for the car to run. I'd also check the new fuel lines, could be one has a kink in it too causing low volume but good pressure.
it's definitly a leak down/bleed off problem. The 2 ends of that spectrum are fuel pump & injectors. With the pressure dropping off that much when you take the clamp off the line, the problem is in the pump/feed lines.

I'd change the pump and if the problem persist, take a good look at the regulator and lines (check the lines first just to be sure...)

 

[Bob Avellar]

There are 2 parts to fuel
1) pressure
2) volume
I understand but I would think with normal pressure reading on the gauge I would have enough volume to supply fuel to start- or at least cough and hiccup or something. Gauge reads steady at all times except when it drops off after shutdown. It usually stays steady for several minutes and then it begins to drop of about 2 lbs per minute or so. Lines have been checked and it was a nice ,neat install. My buddy put them in and he is a neat freak. Thanks for the reply.
We did have a problem with the lines after first installing everything. We had the return line trying to send fuel back to the tank through the vent line. Couldn't figure out why I had 70 psi at the gauge no matter how i adjusted it.. Before I figured out the wrong connection I blew 100psi air through the return line thinking something was blocking the return. Wel, yea- the vent stupid! I don't think I ever blew air into the fuel rail or feed line. I was thinking that the air may have loosened the fuel feed line at the pump or maybe damaged the check valve- but i don't rember blowing through those lines. Wouldn't have a need to since I could tell the restriction was in the return path and not the feed. Funny how the pump should start to fail just cause we put new lines in unless a connection is loose- but that usually happens when I work on stuff. An unrelated problem always seems to happen just to make me think I was the cause. Old pump was a Walro 307 so it isn't a total waste since i will have a new 340.

 

[Rickracer]

I'm not absolutely certain about the TR systems

But on most EFI systems, if they will hold to within 10 PSI of the pressure at shutoff for 20 minutes, that is good.

 

[turbolou]

Reply

I have heard of this before If your static fuel pressure is jack up too high the injectors lock up & won't spray. Verify that you have a reliable guage & the pressure is correct. Good luck! Lou

 

[Bob Avellar]

But on most EFI systems, if they will hold to within 10 PSI of the pressure at shutoff for 20 minutes, that is good.

I would have to agree. When I start it every day it is fine. It's when it sits over the weekend. It will take 2 cycles of ignition on for the fuel pressure to reach 45psi. turn ignition on,listen to fuel pump running, gauge only goes up to 15-25 lbs. Shut off ignition, turn on again, watch pressure build to 45psi. If started once each day the pressure will reach 45 on the 1st ignition on. Kinda like the f pump loses its prime?

tatic fuel pressure is jack up too high the injectors lock up & won't spray. Verify that you have a reliable guage & the pressure is correct. Good luck! Lou

Pressure gauge is brand new. Replaces an identical one that started leaking the glycerin due to someone squeezing the glass. After it was installed it read exactly the same pressure as the previous one. I had 45 psi at key on before startup. Of course when I started the car and the pump began running full time the gauge went up to 75 due to the mixup we made on the fuel return through the vent. I'm sure the gauge is fine. That had me thinking though.

 

[turbolou]

Originally posted by Bob Avellar
But on most EFI systems, if they will hold to within 10 PSI of the pressure at shutoff for 20 minutes, that is good.

I would have to agree. When I start it every day it is fine. It's when it sits over the weekend. It will take 2 cycles of ignition on for the fuel pressure to reach 45psi. turn ignition on,listen to fuel pump running, gauge only goes up to 15-25 lbs. Shut off ignition, turn on again, watch pressure build to 45psi. If started once each day the pressure will reach 45 on the 1st ignition on. Kinda like the f pump loses its prime?

tatic fuel pressure is jack up too high the injectors lock up & won't spray. Verify that you have a reliable guage & the pressure is correct. Good luck! Lou

Pressure gauge is brand new. Replaces an identical one that started leaking the glycerin due to someone squeezing the glass. After it was installed it read exactly the same pressure as the previous one. I had 45 psi at key on before startup. Of course when I started the car and the pump began running full time the gauge went up to 75 due to the mixup we made on the fuel return through the vent. I'm sure the gauge is fine. That had me thinking though.

You say the car doesn't start ? What do you do to finally get it started? When it does start how does it initially run ? Does it act as though it was flooded? Any smoke or clues about that? Maybe you have some injectors leaking down into the clys. All though I think that it is probably in the tank unit. Maybe you unseated the f/pump hose to feed line when you pressurized it with air ?

 

[Bob Avellar]

When I get it started every day there is no smoke to indicate leaky injectors. When I get the car started after having the starting problem it has blown black smoke and sputtered for a few seconds after I get it going sometimes. BUT I think that is due to the extended cranking period. I think maybe there is not a full fuel rail or something going on so that maybe a few cylinders are seeing a small amount of fuel but not enough to start. I don't know Maybe there are multiple problems at work here. Maybe an injector or 2 is a bit leaky along with the supply problem. I also have a gallon of xylene in the tank along with about 5 gallons of 93. I dumped that in just for cleaning puposes.I have so many other things to do on the car (restoration) that I haven't jumped on replacing the pump yet- till I use up some more gas. I 've owned her for 17 yrs and Ive never had a hard starting problem. I had a no start once when the crank sensor went bad but that's it.

 

[wlaukaitis]

Just to add:

When I turn the ignition on, the fuel pressure goes to about 20 psi, (If I cylce again it will go to about 35)I usually have to crank for 5 seconds or so, this my be due to the ECM needing 4 psi oil pressure or for the fuel psi to come up more? I start my car about once a week to keep the cars and my blood flowing