Bullnose Enthusiasts Forum

'86 5.0 EFI Manual No-Start Issue

Classic

List

Threaded

55 messages Options

123

fords4life

'86 5.0 EFI Manual No-Start Issue

Hi all, had a no start on the '86 this morning. I can hear the fuel pump come on, but it is running continuously and not building enough pressure to shut off like it normally does before I start the truck. I let it run and checked for fuel at the schrader valve on the fuel rail, and I have fuel, it just doesn't seem to be building enough pressure and isn't firing. I didn't have time to check for spark, but with the pump not shutting off, I'm guessing I have a fuel issue of some kind. Thoughts?

1986 F-150 SC 2wd 4spd 302EFI Base Model all OEM motor/trans/emissions equipment.

Gary Lewis

Re: '86 5.0 EFI Manual No-Start Issue

Administrator

According to the EVTM you should have an in-tank low pressure pump and a frame-mounted high pressure pump. Do you know which one is running? If the low pressure pump isn't running then the high pressure pump won't have any fuel to pump and can't bring the pressure up.

Do you have dual tanks? If so, can you switch to the other tank to see if that in-tank pump will work?

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

fords4life

Re: '86 5.0 EFI Manual No-Start Issue

I was in my work clothes so I didn't climb underneath, but the sound was in the typical spot under the drivers side frame rail where the high pressure pump sits. I tried switching back and forth between tanks with no change. There was fuel at the rail(used my knife to push on the schrader valve and got fuel immediately), it just doesn't appear to be enough pressure.

Just to confirm, truck turns over just fine, no starter issues, just won't fire.

1986 F-150 SC 2wd 4spd 302EFI Base Model all OEM motor/trans/emissions equipment.

Gary Lewis

Re: '86 5.0 EFI Manual No-Start Issue

Administrator

I would think that any pressure would eventually get the engine to kick over. Maybe not run, but hit intermittently. And while that might point to an ignition or electrical problem, the fact that the pump doesn't stop running like it usually does says it really is related to fuel. And the first test I'd suggest is to put a gauge on the schrader valve.

Is there any chance you are out of gas? Do you see any signs of leaks?

If the pressure is low then it would seem like the high-pressure pump is the problem. However, you said that switching back and forth between tanks didn't make a difference, and that may indicate a problem with the 6-port valve. It determines which in-tank pump is supposed to run as well as where the fuel to the high-pressure pump comes from and where the return from the regulator goes. So a problem with the valve could starve the high pressure pump of fuel, causing low pressure at the rail. And the 6-port valves are known to have problems - I just bypassed the one on Big Blue as it sprang a leak, but NumberDummy says they were a problem from the day they came out.

You can get a kit at the parts store to repair fuel lines, and you could use it to bypass the 6-port valve. But you have to cut the lines and graft in a line from the kit. That means you won't have the other tank available unless you repair what you cut out. And, since the gauge circuit goes through the 6-port valve you will have to wire around it, leave the valve but not have it being used, or do w/o a gauge.

Perhaps there's another kit that has the right connectors to let you just bypass the valve w/o any cutting? Maybe Bill knows?

Gary, AKA "Gary fellow": Profile

fords4life

Re: '86 5.0 EFI Manual No-Start Issue

So....had to run home for a few minutes and truck fired right up. Fuel pump turned on with key in run position and shutoff a few seconds later just like always.....I'm stumped....This is going to be a fun one to figure out I'm sure.

1986 F-150 SC 2wd 4spd 302EFI Base Model all OEM motor/trans/emissions equipment.

Gary Lewis

Re: '86 5.0 EFI Manual No-Start Issue

Administrator

I hate intermittent problems. They are so hard to find. Anyway, glad it ran for you.

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: '86 5.0 EFI Manual No-Start Issue

Administrator

In reply to this post by Gary Lewis

Gary, the 6 port tank selector on the EFI is not the motor operated beast on the hot fuel handling package 460. It is a combination reservoir and tank selector and on the 1986 models has a filter in it.

The fuel tank selector switch (page 104 of the 1986 EVTM) shows it as being the only thing common to both in-tank pumps. The relay and inertia switch are in the circuit before the switch and would also affect the high pressure pump.

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

vjsimone

Re: '86 5.0 EFI Manual No-Start Issue

In reply to this post by fords4life

The fuel pumps running continuously when the engine is not under power, is a fairly common sign of a corruption in the ECA/Computer.

Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"

Gary Lewis

Re: '86 5.0 EFI Manual No-Start Issue

Administrator

Vinny - Is that intermittent? He's had it happen and then go away.

And, what causes it? Just a bad ECA?

Gary, AKA "Gary fellow": Profile

85lebaront2

Re: '86 5.0 EFI Manual No-Start Issue

Administrator

Gary, ECA and FPR along with the inertia switch will affect all the pumps, Other than the actual connector plugs on the tanks, the tank selector switch is the only electrical item in the circuit that does not affect the high pressure pump, even the ground, G701, is the same.

Bill AKA "LOBO" Profile

vjsimone

Re: '86 5.0 EFI Manual No-Start Issue

This post was updated on .

In reply to this post by Gary Lewis

I have not seen it intermittent, but I don't know if folks in the past have noticed an intermittent period prior to a total failure.

Other than a short to ground in the Fuel Relay circuit, the Fuel Relay is controlled by the ECA.
EDIT; This ground wire also leads over to the OBDI test connector, so, if this wire shorts to ground, you would experience continuous running fuel pumps.

I don't know what goes cattywampus in the ECA when this happens. I've seen in the past, that 99% of the run-on Fuel Pump scenarios were ECA related.

There is a timing circuit that is triggered off the PIP signal, if the circuit does not see a PIP within a second, the ground is removed from the Fuel Relay. This is why when the key is turned to ON, the fuel pumps only run for a second.

So, it is possible that the electronic device (FET?) that provides the ground is failing, or the circuit that controls this device is failing. (Best guess). So, I could see where the circuit controling the grounding component could fail and keep the device in ground path mode.

I'm guessing when this occurred, he probably had no spark as well.

Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"

vjsimone

Re: '86 5.0 EFI Manual No-Start Issue

In reply to this post by fords4life

“I can hear the fuel pump come on, but it is running continuously and not building enough pressure to shut off like it normally does before I start the truck.”

For clarification, there is no “shut off” when the pressure reaches the maximum capability of the High-Pressure Fuel Pump. As designed, as long as the engine is running the fuel pumps will run. Fuel pressure control is designed into the Fuel Pressure Regulator.

“I let it run and checked for fuel at the schrader valve on the fuel rail, and I have fuel, it just doesn't seem to be building enough pressure and isn't firing.”

Fuel Pressure readings are only a guess without using a pressure gauge.

Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"

vjsimone

Re: '86 5.0 EFI Manual No-Start Issue

In reply to this post by fords4life

Was it raining when this occurred ?

Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"

fords4life

Re: '86 5.0 EFI Manual No-Start Issue

It had rained pretty hard that night.

What do PIP and FET stand for?

I did not have time to confirm if I had spark or not unfortunately, so who knows.

Completely agreed on the fuel pressure, I only know that I had fuel flowing through the rail, no idea on how much pressure or volume was moving.

Thank you for the clarification on the fuel pump shutoff being timing instead of pressure based. I had apparently read some misinformation elsewhere as to what caused them to shutoff.

1986 F-150 SC 2wd 4spd 302EFI Base Model all OEM motor/trans/emissions equipment.

vjsimone

Re: '86 5.0 EFI Manual No-Start Issue

FET, is Field Effect Transistor, but I don’t know if that is what the 3-legged components are in the ECA providing the grounds. There is some technology of Driver/Transistor or electronic switch in the ECA heatsinked around the edges, but I have not read the numbers off the devices to date.

The PIP is the pulse output from the Hall-Effect device in the Dizzy. As the Dizzy shaft spins, the slotted metal yoke attached to the shaft makes and brakes the magnetic field to the Hall-Device. That PIP pulse is channeled thu the TFI/Ignition Module to the ECA. As long as everything is working as designed, when the Dizzy is spinning, you have a Pulse.

This is why the fuel pressure relay does not energize longer than 1 second when the engine is not running, and key is turned to on. No pulse, timer circuit allows a 1 second relay turn on until the circuit sees another PIP pulse. As long as the frequency of PIP pulses is greater than 1 pulse per second, fuel pumps run continuously.

The PIP also excites the SpOut circuit which may adjust the Timing circuit provided by the TFI/IM to switch the Coil On/Off, and provide the signal to a tachometer if installed.

Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"

vjsimone

Re: '86 5.0 EFI Manual No-Start Issue

In reply to this post by fords4life

We have seen a few folks that only had the pump run-on issue when it was raining, maybe high humidity/dewpoint…..

One guy replaced his ECA with 2 new ECAs, both had this run-on when it rained, he purchased a used JY dog ECA, and this solved his problem.
I believe one of the other guys had water running in under his dash and into the ECA.

Vinny... "Do All Scheduled Maintenance Prior To Troubleshooting" "Resolve All Known Issues Prior To Troubleshooting"

sgauvry

Re: '86 5.0 EFI Manual No-Start Issue

Vinny is correct with regard to this because that guy was me. With cold starts it started right up. Once the engine was hot, it would not start. If I let it cool, it started right up. From what I read, seems that may be your case also.

Steven A. Gauvry - 1985 F150 5.0 EFI

fords4life

Re: '86 5.0 EFI Manual No-Start Issue

So....this problem has come and gone twice, and now is here to stay. It's been 2 days since the last rain and still no start this morning. With the previous lighting issues I had that mysteriously went away, I'm guessing I have a ground problem somewhere, but wondering if anyone has any advice on where to start? My other truck decided it didn't want to start so I'm kind of SOL on trucks and I think the '86 will be easier to get going so I'm planning on attacking it tonight.

1. Everything under the dash around the ECA looks clean/no water. I have not removed the ECA yet.
2. I need to verify that I have spark while cranking.
3. I will review the EVTM and can start their, but I know some of those procedures are designed around a breakout box which I don't have.

Thoughts on things to check without just throwing parts at it.

TIA
Nathan

1986 F-150 SC 2wd 4spd 302EFI Base Model all OEM motor/trans/emissions equipment.

Gary Lewis

Re: '86 5.0 EFI Manual No-Start Issue

Administrator

You are on the right track by checking for spark. But if you have it you should then check for fuel pressure. By '86 I think the EFI system had a Schrader valve which you can depress to see if you do have pressure. If not, then you need to see if the fuel pumps are running.

As for grounds, Page 10 of the 1986 EVTM shows a special ground for those trucks with the ECA. (My version has it called out.) You might check that.

Gary, AKA "Gary fellow": Profile

fords4life

Re: '86 5.0 EFI Manual No-Start Issue

I need to see if I can find a gauge locally to go onto the fuel rail schrader valve, but the last time it happened, I had pressure, just not sure how much. That and the sound of the fuel pumps running lead me to believe the issue is ignition/computer related, not fuel system related.

1986 F-150 SC 2wd 4spd 302EFI Base Model all OEM motor/trans/emissions equipment.

123