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Finally No Start

1984 Cougar 3.8

As a number of forum members know I've had an intermittent no-start for some time.
Looks like finally failed.  Troubleshooted the fuel system today:

1)  Removed fuel pump relay and jumped through to just drive both pumps.
2)  Checked volume -- for a 10 second run per shop -- both on the supply side and return side at the throttle body.
....Results are:  Supply side:  11 oz.
.......................Return side    5 oz.

Per shop 10 second run on return side should be .GT.  9.5 oz.

So it appears I have a blockage somewhere within the throttle body.

Any suggestions as most likely places blockage would cause such a volume reduction (e.g.
(e.g. body itself, injector screens) or am I barking up the wrong tree?

Finally No Start

Reply #1 –
I am confused . What did you prove with this test???  Are the pressures correct?? And was the other systems checked as well. Spark ETC?? Just asking. I gather you think their is a restriction. But if the vehicle is not running whatever is cousing the difference you feel is causing this NO START?? I am not following what you are saying. Sorry. Can you be more specific and how did you do the test. Can you post photos of the place you are testing volume. I assume the engine is not running when testing Correct!! If memory serves me the TB has a built in regulator??. Is the injectors spraying fuel when cranking!!! Thanks
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Finally No Start

Reply #2 –
Quote from: TOM Renzo;391735
I am confused . What did you prove with this test???  Are the pressures correct?? And was the other systems checked as well. Spark ETC?? Just asking. I gather you think their is a restriction. But if the vehicle is not running whatever is cousing the difference you feel is causing this NO START?? I am not following what you are saying. Sorry. Can you be more specific and how did you do the test. Can you post photos of the place you are testing volume. I assume the engine is not running when testing Correct!! Thanks
Chrysler uses volume tests rather than pressure tests on their diesels. If his target is correct, it proves fuel pump is A OK. If there is a blockage, it is on the other side of where the supply side was tested. I would expect the return volume to be the same as supply volume if the injectors don't fire, because there would be no fuel usage. Question is, is the injectors fireing? Is the problem even fuel related? I would expect it to be ignition problem or something causing the injectors not to fire.

Finally No Start

Reply #3 –
Mr. Renzo:

Quote
What did you prove with this test???

Attempting to check if both fuel pumps are functioning OK.

As Chrome stated - and my opinion also --
Quote
fuel pump is A OK. If there is a blockage, it is on the other side of where the supply side was tested. I would expect the return volume to be the same as supply volume if the injectors don't fire, because there would be no fuel usage.

Chrome is correct vehicle was not running or even cranking.  Just running the pumps by themselves.
All volume was checked at the throttle body connectors or in the case of supply the line right before it connect to the TB.

When vehicle was running injectors worked -- but volume unknown at injectors.  Fuel pressure was right on at 39 PSI. 
Right now vehicle cranks fine, trys to catch and then fails.
Tried starting fluid but again no start.
Getting spark  (though orange) on #4 and #6. -- only ones tested
Have gone over electrical over and over again and finally came conclusion elsewhere.
Based on my internet reads, fuel issues cause some funny things to occur which leads one to go down the electrical path.

Can't explain why no start with starting fluid (did get a backfire once), other than injectors may be putting out some gas
but not enough to start and when starting fluid added causes an overly rich condition.
Hence my original question re the TB as where I should start looking for a blockage. 
Injector screens my best guess but hope someone who's rebuilt these TB's may have more insight.

Finally No Start

Reply #4 –
Quote from: dw85745;391724
1984 Cougar 3.8

As a number of forum members know I've had an intermittent no-start for some time.
Looks like finally failed.  Troubleshooted the fuel system today:

1)  Removed fuel pump relay and jumped through to just drive both pumps.
2)  Checked volume -- for a 10 second run per shop -- both on the supply side and return side at the throttle body.
....Results are:  Supply side:  11 oz.
.......................Return side    5 oz.

Per shop 10 second run on return side should be .GT.  9.5 oz.

So it appears I have a blockage somewhere within the throttle body.

Any suggestions as most likely places blockage would cause such a volume reduction (e.g.
(e.g. body itself, injector screens) or am I barking up the wrong tree?

The regulator is restricting the flow more that it normally would to get the pressure to 39psi.
The available flow on the supply side is too low.
Clogged filter. Pinched fuel line. Weak pump. Or anything else you can think of that would reduce the supply volume.
This is what the above test is indicating.
This is not to say you don't also have other problems. Sometimes we can tie ourselves in knots trying to theorize all of our symptoms down to one solution.

Finally No Start

Reply #5 –
Quote from: softtouch;391751
The regulator is restricting the flow more that it normally would to get the pressure to 39psi.
The available flow on the supply side is too low.
Clogged filter. Pinched fuel line. Weak pump. Or anything else you can think of that would reduce the supply volume.
This is what the above test is indicating.
This is not to say you don't also have other problems. Sometimes we can tie ourselves in knots trying to theorize all of our symptoms down to one solution.
That would be true if the info he has for correct volume is incorrect. Honestly, I don't know. I have never seen this test ran on a gas engine. Don't have a clue as to what volume it should have.

Oops! I just discovered that you thought his volume test was fuel pressure. His fuel pressure is 39psi right where it should be. All is good up to and past pressure regulator.

Finally No Start

Reply #6 –
Try a node light. See if the injectors are getting the signal to fire. Don't know your system too well, but if it is not getting the signal to fire, it could be a cam and or crank sensor. Could be a bad wire somewhere. PCM could also be the problem, but that would be a last resort and not likely.

Finally No Start

Reply #7 –
How do you build PRESSURE IF YOU DONT RESTRICT FLOW???
The return is always restricted that is why their is a regulator in the return. NO RESTRICTION NO 39 LBS!! Example it is like a garden hose without a nozzle. Once you install a nozzle the pressure in the hose climbs. Without a nozzle the pressure in the hose is very low. The return side is restricted their fore it should not have the same flow as the supp;i

Return is on the restricted side!!!

Noid light is mandatory for pulse confirmation. I agree with Chrome on this 100%

Tried starting fluid but again no start.

Then you dont have fire or the compression is LOW. Did you check the COMPRESSION. And spark. If it does not start with fluid then something is wrong with something ELSE. Make sure you have spark at the PLUGS. All of them and check the compression.
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Finally No Start

Reply #8 –
Thanks all for responses:  What I did is "almost" identical to the shop.  (p. 24-35-5)
Shop test suggested to disconnect wire harness at high pressure pump and use an auxillary one and a separate B+.
Shop says fuel pump OK if:

1)  pressure reaches (35-45 psi)
2) volume at return line is for 10 seconds is 9.5 oz or greater
3)  fuel pressure remains at 30 psi immediately after shutdown.

Volume test FAILED (at return) per above, but before troubleshooting the pumps thought I'd check the supply side which IMO gave good results.
That IMO seems to indicate some kind of restriction within the TB -- hence this thread.

--------------------------------------------------
Since injectors are NOT firing under this test, don't see where noid light would help at this point.
Can't explain the starting fluid issue other than as previously stated.

SOFTOUCH's comment:
Quote
The regulator is restricting the flow more that it normally would to get the pressure to 39psi.

This makes sense

Quote
The available flow on the supply side is too low.

Not sure if this is a "statement of fact" or suggestion. 

QUESTION Softtouch -- Any idea what the volume should be on the supply side??

ADD:  Based on my calculations:  (see shop 24-35-2) for a 100 L (26.4 gal per hour pump) I should get 9.38 oz in 10 seconds, 
        For a 60L pump (15.9 gal hour) I should get 5.65 oz for 10 seconds.
        Replaced high pressure pump several years back  (about 4) and as I recall was the 100L.
        I'm exceeding that on the supply side.
        That coupled with fact I put in a new fuel filter couple weeks back and the old still appeared to be OK (no junk).
        So still going with a blockage somewhere in the TB. 

        Guessing that gas flow is just from supply side connection, to pressure regulator, to injectors then out the return.
        Can anyone please confirm ?

Quote
This is not to say you don't also have other problems.

Always possible.  THanks for the reminder.

David

Finally No Start

Reply #9 –
I have a couple of questions:

1) Does your car have a low pressure lift pump in the tank and then a high pressure booster pump that is frame mounted?
2) Is the pump(s) the factory unit(s)?
3) Have you dropped the tank?  If so what was the condition of the tank i.e. any debris in the bottom and what did you do i.e. replace pump and/or sock filter?
4) Have you chased all the fuel lines and visually inspected for kinks or crimps?
5) I think I remember you replaced the fuel filter but wanted to double check.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Finally No Start

Reply #10 –
Seems to me that if the engine wont fire with a shot of (starting Fluid) why spend so much time on fuel delivery. If i may why does it not start when shot with starting fluid. Just curious??

If you system was restricted and the pressure was  as you claim 39 PSI. Then their would be more then enough  fuel at the injectors. you fall within factory specks with the test you have dun!
Lack of fuel should be a non issue if the return is blocked. I or you are not getting what is going on here. If restricted on the return and supply is ok then more fuel would be available at the injector. So if the return is blocked the engine would run RICH. That is what happens when a return line is kinked or restricted. The engine sees more fuel with injector pulse. Back to starting fluid!!! Why does it not start with a shot of this stuff. If you lack fuel a shot of this stuff will fire that engine in a second. I am missing something here!!!

OK so does the car have proper cranking or pump run pressure. App 35 Lbs ??? And does the supply side have the proper flow??? And is both pumps working properly??? And a no start with a shot of fluid wont start it i am going to assume something is bad other than fuel supply. Because 39 LBS of pressure is good enough at the injector rail for the injectors to work. I am missing something here. Can you clear it up a bit!!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Finally No Start

Reply #11 –
coil

Finally No Start

Reply #12 –
Darren re your questions (Answers under each quesiton):
Quote
I have a couple of questions: 

1) Does your car have a low pressure lift pump in the tank and then a high pressure booster pump that is frame mounted?
Yes
2) Is the pump(s) the factory unit(s)?
High pressure new -- about 4 years ago;  Low pressure original.  >> The Low is the one I thought originally may be bad
3) Have you dropped the tank? If so what was the condition of the tank i.e. any debris in the bottom and what did you do i.e. replace pump and/or sock filter?
No, tank never dropped.
4) Have you chased all the fuel lines and visually inspected for kinks or crimps?
No, but consider this remote possibilty.  Single owner, only driver;  Has plastic lines and haven't touched lines except for filter replacement
and disconnect from TB.
5) I think I remember you replaced the fuel filter but wanted to double check.
Yes - short time ago.  Only had about 1000 mile on other, but replaced just to see if any trash in filter.  None I could visually see by dumping filter out backwards.
Still have filter I removed and may cut it open for a look see.

Tom:
Quote
Seems to me that if the engine wont fire with a shot of (starting Fluid) why spend so much time on fuel delivery.

Couldn't agree more.  HOWEVER and I mean HOWEVER, I've been over this vehicle with the Intermittent No-Start, and even replacing the distributor (for a new stator) would not allow it to start.
At that time, about 2-3 week before this Final No-Start, taking off the return line (for whatever reason ???) allowed it to start right up.  Go Figure!!!



Stangman

Quote
coil

Always a possibilty esp with orange spark at plugs..  Easy check, but previously checked OK even with orange spark at plugs.

Finally No Start

Reply #13 –
Quote from: TOM Renzo;391758
How do you build PRESSURE IF YOU DONT RESTRICT FLOW???
The return is always restricted that is why their is a regulator in the return. NO RESTRICTION NO 39 LBS!! Example it is like a garden hose without a nozzle. Once you install a nozzle the pressure in the hose climbs. Without a nozzle the pressure in the hose is very low. The return side is restricted their fore it should not have the same flow as the supp;i

Return is on the restricted side!!!

Noid light is mandatory for pulse confirmation. I agree with Chrome on this 100%

Tried starting fluid but again no start.

Then you dont have fire or the compression is LOW. Did you check the COMPRESSION. And spark. If it does not start with fluid then something is wrong with something ELSE. Make sure you have spark at the PLUGS. All of them and check the compression.
Did you mean supply side? Injectors need 39 Psi not the fuel tank. I do agree, a fuel pressure test is needed to make sure regulator is functioning.

Finally No Start

Reply #14 –
Quote from: dw85745;391767
--------------------------------------------------
Since injectors are NOT firing under this test, don't see where noid light would help at this point.
Can't explain the starting fluid issue other than as previously stated.

If you have determined you have fuel at the injectors, it is time to see if you have fuel coming from the injectors. I am concerned that starting fluid will not start it. Tells me it is not fuel related.