88 Mark 7 no start

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joew

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well well well hello.. finding this place is like getting a belated Christmas present .. I guess I'll put off taking this car to the repair shop for a few days.

I have a '88 MK 7 LSC, 5 Liter EFI, HO engine. 200K miles on the car, only about 30 k on the new engine.

One day hard to start, the next it wouldn't start.
Cranks normally but no fuel? It will start by priming the intake maniifold with gasoline or starter fluid. As is normal for this car, it's a rocket ship thereafter.

Turn the key a couple times and fuel pressure at the schrader valve is strong so fuel pump at start is OK, pump relay is OK.. Since priming the engine works, spark during cranking is OK too? There are no running problems at all and no restarting troubles if the engine stays warm.

One other clue is the idle is low when cold started .. near 800 instead of 1200 RPM. The computer seems to think the engine is warm?

I bought a $34 code reader. Key On Not Running code is 34. This code is also in the EEC memory.

(I have all service manuals except the one i need.. "Engine/Emmissions diagnosis Vol H " but i'm gonna order that immediately.)

So, code book says stuff about code 34, like :

Insufficiient EGR flow (or not opening properly)
EVR - EVP sensor is/was high - EVR
PFE - PFE sensor is/was out of range - PFE
Defective EGR pressure transducer sensor
.........
At this point i'm sorta lost. I thought i'd ask you people before buying new EVP or PFE or EVR sensors, assuming i manage to discover what and where they are. Hopefully i've provided enough info to diagnose this no-start problem or at least narrow it down to replacing a couple sensors. Any advice is most appreciated and i'll do my best to answer any questions.
.......
btw.. i'm not bragging but i got lucky.. and got this car for free about 2 years ago. Lincoln searched but could not find an ABS (yellow dummy light) problem and wanted $3500 for an entire new brake system. Headed for the junkyard?
I (somewhat unwillingly) took the car and after a few days pulled the rubber brake hose off the resevoir.. I had a tin can ready but nothing came out (??) The built-in filter at the bottom of the brake fluid reservoir was clogged up.. The pump was overheating/shutting down intermittantly. Brake-fix cost me $6 for a salvage yard reservoir. I guess Lincoln limited it's $100 diagnosis to a code reader or something..
 
You can pull of the EGR and IAC to clean the carbon out of them. This is often the cause of a code 34. Use some carb cleaner and get all of the carbon out of there. This would be a good start, but most likely not the overall cause of your starting problem.
 
Thanks Josh..
I pulled the EGR and there was only about 1mm of carbon coating the ports and parts.. It gave me an opportunity to put a ohm meter on the EGR Valve Postition Sensor. I'm sure it's a common potentiometer. Tested resistance between the 3 leads and resistance changed smoothly according to the degree the plunger was depressed. Resistance range is from 4.16K ohms down to a couple hundred ohms. Seems OK to me. The assembly is vacuum tight. The EGR valve seals tight.

Pulled the IAC but there was just a dusting of carbon so i didn't mess with it.. visual examination showed nothing unexpected.. mounting bolts were tight.. electrical connector was secure. This engine has only about 30K on it and always ran well; passes Smog without any problem.

The electrical/emmissions diagnosis manual i want is "Printed to Order" for (i think) $69 from Helm but at least it's available. In the meantime i'll keep looking under this hood.. maybe come across a bad wire or vacuum connection .. a fried sensor or something obvious.
 
Need advice:

I removed the EGR Vent Solenoid. It's mounted on the front right upper strut housing. It has red and green vacuum lines. The green line goes to the EGR and controls how far open the EGR is. Red line is to vacuum source.

This vacuum valve's 's solenoid has a two wire plug. Variable venting is achieved by voltage pulses sent to the solenoid... kinda like pulse width modulation.. wide pulses keep it open (or maybe closed?) for a longer period. When disconnected, this valve vents in any direction so i'm not sure if the valve idles in the middle of it's stroke or if it's broken or if it's healthy..

Anyway, i removed it from the car and checked for continuity in the solenoid winding.. 45 ohms. Seems ok to me but some of the winding could be shorted.. i don't have specs.

How about the mechanical valve it's supposed to control? I put a 6 volt battery on the connectors expecting to hear a "click" but nothing.. then tried 9 volts.. still nothing. I don't like this idea because i don't want to burn it up so i'll hold off on 12 volts.

Anyone know if the above is normal or does it indicate some problem with this valve or it's solenoid?
 
OldSchool1 said:
Maybe I missed something Joe but did your first solution get the car to start?
Click to expand...

Sorry if i wasn't clear about it.. Nothing but priming the engine with a squirt of gasoline will get it started. That is my only solution so far.

Code 34 points at something related to EGR. Code 34 continues to be the output.

The EGR valve and the position sensor mounted to it appear to be OK.

I have questions about the EGR vent solenoid (which is what meters vacuum and actually positions the EGR, afaik) but I don't know how to properly diagnose this solenoid and it's vacuum valve.
 
"I'm not a mechanic. I just play one on the internet."
I'd replace the fuel filter and air filter and spark plugs and work from there.

joew said:
...I (somewhat unwillingly) took the car and after a few days pulled the rubber brake hose off the resevoir.. I had a tin can ready but nothing came out (??) The built-in filter at the bottom of the brake fluid reservoir was clogged up.. The pump was overheating/shutting down intermittantly. Brake-fix cost me $6 for a salvage yard reservoir. I guess Lincoln limited it's $100 diagnosis to a code reader or something..
Click to expand...

I've never thought of checking there for brake problems.

Thanks.
 
I've never thought of checking there for brake problems.

Thanks.[/QUOTE]

Maybe someone else can benefit from this.. Here's how i understand what happened.

Symptoms: A sudden lack of power brakes.. like when the engine dies. Hard pedal pressure will stop the car in time if you're lucky. Yellow Check-ABS warning light on. After a delay of about 5 minutes brakes were back online. It happened more often in stop 'n go driving (only had to happen to me once before i got scared enough to get to work on it).

The hydraulic pump has an automatic shut off after 20 minutes of continual running. Since the filter inside the reservoir was clogged the accumulator was difficult to keep at top pressure (especially if you use the brakes a lot.. stop 'n go) so, the pump ran continuously. The pump doesn't like to vacuum in fluid.. it expects a steady, free flow of fluid. Perhaps it was cavitating or something like that too.

Anyway, the source of the intermittant problem was an overworked pump.

At the junkyard, aside from the reservoir i also took a pump and accumulator just because i like to play with hydraulics and i didn't have a 12 volt pump... paid about $30 total if i recall.

Both my used and the used replacement reservoirs were black inside at the bottom. You cannot see the paper element filter in there. It's way down at the bottom near the outlet. At the junkyard I removed the hose and fluid drained out so i took it. Reservoir is one piece so I cut the old one open to examine the filter and perhaps clean it and "weld" the plastic box back together some day. (like that will ever happen..)

It's a mystery to me where the garbage that clogged the filter came from.. it was a lot of thick creamy black goo.
 
Car starts normally and it seems to be fixed .. but I'm not real happy since it sorta fixed itself.

Recap: The car ran fine but wouldn't start (but only when cold) without priming the intake manifold with Starter Fluid or gasoline. After changing plugs, rotor and distributer cap, fuel filter .. cleaning the EGR and inspecting all the sensors related to a Code 34 (something related to EGR) and most temperature sensors, I decided to check for spark at start-up and at idle.. This is where the fun starts.

So, i hook up a neon spark tester to a plug boot and a remote start switch at the starter solenoid.. turn the ignition to Run and remove the air intake hose... Open the throttle butterfly, spray some starter fluid in there and hit the button. POW! .. a nice big backfire.. singed eyelashes.

I'd probably be more upset and feel stupider than i now do except that the scary little experience fixed the starting problem..

So, here's what i guess happened. The explosion in the manifold sent sudden high pressure through a bunch of vacuum lines. One of the lines or some device connected to them was clogged up.

Anyone got a better idea of what happened? Any opinions on a likely candidate for the clog? Although i'm not gonna complain real loud, I don't like it when things fix themselves while i remain clueless about the source of the problem.
 
Perhaps the fuel pressure regulator was sticking open and returning too much fuel to the tank so the injectors weren't firing a solid stream of fuel while cranking. The pressure regulator does have a vacuum connection directly to the underside of the air plenum. Or at least it does on a non-HO 5.0. I don't imagine the HO's fuel system would be all that different.

Otherwise, thats a pretty amusing way to have something fix itself. My friend had a Cordoba that wouldn't run right in the morning till you got it to give a solid backfire. He would just pull out of the driveway after letting it warm up and floor it. It would stumble and miss, then give a loud bang thru the carby and would thereafter run perfectly. If he didn't tromp it, it wouldn't backfire and would continue to run in a generally crappy manner for as long as you drove it. I just figure it was posessed by demons remaining from the LeanBurn system it was inflicted with by the factory.
 
Yes, it does have a vacuum line attached. There's some sort of balance between fuel returning to the tank and the degree of vacuum... Air/fuel mix does need to be especially rich when cold starting.
After cranking for just a moment and then venting the schrader valve on the fuel rail, there was pressure but it may have been inadequate. Although it's "fixed" I'm gonna take it in for an examination and i'll mention your suspicion about the regulator.

After listening to your friend's story, maybe this whole idea of forcing some (safe) amount of pressure through the intake manifold is a legitimate way to fix some things. I'm not familiar enough with it to foresee any danger to components but it's one fast way to clean out all the lines. No doubt that occasional backfires would be predicted by the design engineers. I checked and found no vacuum lines or caps that got blown off but i'm still a bit worried about that possibility.

btw, I can't find any specs as far as power output on this stock HO engine. All i know is it's got some snot.. was happy to see headers (?!!?) the first time i popped the hood.
Either the manuals don't mention power output or i just can't find it. If anyone knows, i'd appreciate the info or a link to the info.
 
Thanks for the link. Lots of good info including the stuff i was curious about. The page on cleaning the headlight lens' will come in handy. I didn't want to take the chance of making things worse by attempting to polish out the dull yellowish haze, but I am now inspired to give it a go.
 
I went 4 days without starting my Mark VII. Temps were below "0" and I couldn't get it started. Last night after work temp rose to 15 degrees and wa-la it started right up!!

Must not like the cold!!
 
Fixed for good.. (no start only when cold) The problem returned so I took it to my mechanic and they found a bad solenoid.. not the fuel pump solenoid but another fuel-delivery solenoid. I think he called it the injector solenoid.

I asked if they found it with a diagnostic but these older vehicles don't have a procedure that can pinpoint problems like the newer cars. Code 34 (EGR related) was what i got from my code reader but it had nothing to do with the problem.

I guess this injector solenoid allows the deliverery of fuel during cranking.. then i guess the computer takes over once the engine is started. Cost me $133 total.
 
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