Gen 2 Mark VIII will not start after motor swap

R

renkenj

LVC Member
Joined
Jun 25, 2009
Messages
30
Reaction score
0
Location
DFW
I am new to this forum as a registered member, but I have been reading and learning here for a while now. It's great to be in the club.

I am a new Mark VIII owner but unfortunately not yet a new Mark VIII driver. I'll explain briefly. I bought a Black '98 LSC for a good price, knowing full well that it had some major engine problems and I figured I would ultimately replace the engine. It had a failing head gasket but it did run and I was able to drive it a few miles. I quickly decided to just go ahead and get a used engine and pay someone to put it in for me since I don't have all the tools or the space to do a complete swap. I purchased a warranted engine from a salvage yard out of a (supposedly) running '97 Mark VIII.

Fast forward to this week. The new engine is in the car and all hooked up and ready to go, but it won't start up. It cranks over just fine, but it won't fire up and run. At this point in the story, I am relaying what I am hearing from the mechanic, both when I was standing there watching him for several hours, and over the phone while we try to troubleshoot.

We are getting both fuel and fire. Fuel pressure reads normal at 45 psi. The plugs are new and correct. The coils are from the old engine and were working fine. The wiring harness from my old engine was swapped over to the new one. The intake and fuel injector/rail assembly was swapped over as well. A scanner connected to the OBDII port is reading data, but not throwing any codes. The crank and cam sensors have been checked and swapped from the old engine to the new one and then back again. An aftermarket Jet Performance chip was removed from the computer as well as an aftermarket alarm and remote start system, just to eliminate unnecessary variables. The battery seems to be good and has been connected to a charger throughout the process.

Everything seems right, but after three days of fiddling on this issue, I know my mechanic is probably ready to cut his losses and I'm anxious to have my car done. I've searched and searched here on this forum and elsewhere and I can't find anyone else with this problem after a swap. Could the '97 engine and '98 car be an issue? Does the computer need to be reflashed? Is there a sensor we're overlooking or a sneak circuit with a blown fuse?

Any thoughts on the issue are invited and appreciated. I look forward to some wisdom from the veterans!

Thanks!!!
 
fuel air spark. if you've got fire then check the MAF, TPS, IAC. also make sure its not flooded (hold down the gas pedal while cranking or pop out the spark plugs for a while) you need to scan the motor to make sure PATS isn't the problem and check for error codes. Go around and have a second set of eyes look for any missing or loose connections.
 
If you have fuel and fire you should get something a pop cough sputter even with a busted cam. Hell these things will even run in the limp home mode with no ECM support.
My 2 cents says check the pats, spark, and ECM , I had a friend pull a flip chip with the vehicle power on and wipe the program.
 
Thanks, guys. I will ask my guy if he's confirmed those sensors. I know he was messing with the MAF when I was there looking over his shoulder once, but not sure about the TPS. Good call. I had a '90 Bronco with a TPS problem now that I think of it. (Office Space flashback!)

Yes we were holding the throttle all the way open with no results. At one point it was flooded and he took the plugs out to let them dry, but I'm not certain whether that problem is persisting. I suppose that it could be.

To the best of my knowledge, he was testing the spark with a simple test light designed for the purpose.

I was wondering about the PATS. I did some reading on that but what I understood from it was that it wouldn't even let the engine crank if that were the problem. Will a SnapOn scanner test for that? I think that's the scanner he has. The keys I have are aftermarket programmed keys. I cannot get the originals, though everything had been functioning with the old engine.

I'll admit, I've always worked on older, less complicated cars and paid someone to work on my newer cars. This is a whole new experience for me!
 
Tiltedhalo said:
If you have fuel and fire you should get something a pop cough sputter even with a busted cam. Hell these things will even run in the limp home mode with no ECM support.
My 2 cents says check the pats, spark, and ECM , I had a friend pull a flip chip with the vehicle power on and wipe the program.
Click to expand...

It will spit and sputter just a little bit, usually with the throttle wide open. I'm with you, there's gotta be something disabling it like the ECM or PATS.
 
Update: The same problems described above persist after checking the sensors mentioned above. The car seems to be flooding. If you "trip" the fuel cut-off switch in the trunk, it actually tries to run for a second or two as the fuel dries out.

We have a person coming over later on who is more familiar with Ford electronics, so maybe he can spot something out of place.
 
Make sure your vacuum is routed to the fuel pressure regulator and relief valve. If its flooding that easy there is a problem in the fuel delivery, to check pull the fuse to the fuel pump hit it with a small blast of stater fluid if it runs for a second or two you know the problem.
 
Update: Vacuum problems?

Update: I went to visit the mechanic today to continue to help troubleshoot the cause for the flooding, apparently preventing it from starting. When I checked the fuel pressure regulator, I discovered that there was no vacuum on the line. I checked a few other places and discovered that there is no vacuum at the ports on the intake when cranking the engine. Shouldn't there be vacuum? I tried cranking another Lincoln with a 4.6 SOHC and it had vacuum at the intake.

We took the intake off and checked the gaskets and seals there and cleaned up the IMRCs (one was partially stuck open), put it all back together and still no joy. Exact same condition. It will almost start with the cylinders and plugs dry. If the fuel pump is switched off it will run until fuel runs out. Or if the fuel pump is on, it will run until it floods out. It only runs for two or three seconds though.

We have already checked compression and each cylinder has about 180 psi, so it would appear that the valves are seating properly. Do I have a vacuum problem?

Thoughts...
 
Agreed, but if the regulators operate off of vacuum, and there is no vacuum when it is cranking.....am I missing something?

The regulators and injectors are know to be good, that is, it was on a car that had been running the day before and transfered on to this engine as an assembly during the engine swap.
 
rayner601 said:
I gotta ? What kinda car did the injectors come off of? Maybe they're too big?
Click to expand...

They were both Gen 2 Mark VIIIs. If you see earlier in my post, you'll see that I had a (sort of) running '98. Got a salvage motor from a '97 and stripped it down to a long block. All the sensors, intakes, wires, COPs, etc. were transfered from my original running engine to this replacement engine. Can't find any missing lines or wires and at least 6 people have given it a once over to check for problems.

Original engine had a blown head gasket and a bad knock.
 
renkenj said:
Agreed, but if the regulators operate off of vacuum, and there is no vacuum when it is cranking.....am I missing something?
Click to expand...

The FPR will still function without vacuum. Hell, that's how you're supposed to check fuel pressure, with the vacuum line off it.

You said the car floods when trying to star it with the fuel pump connected. Check the return lines. Maybe one of them is pinched.
 
Ok, long shot. What type of fuel injectors? some one could have replaced the stock injectors with high impedance EV6's with pig tails. The ECM will slam them wide and fry.
 
Frogman said:
The FPR will still function without vacuum. Hell, that's how you're supposed to check fuel pressure, with the vacuum line off it.

You said the car floods when trying to star it with the fuel pump connected. Check the return lines. Maybe one of them is pinched.
Click to expand...

I didn't know that about the vacuum line being off to check the regulator. Hmmm? Well, maybe it's another separate problem, but shouldn't there be some vacuum at startup?

A pinched line is possible. I know a brake line got pinched a little once before under a different situation so it's worth looking in to. I don't think it was pinched when we drove it into the shop under it's own power, but I suppose something could have gotten pinched while putting it up on the lift. I'm away from the car so I can't visualize if the lines run near any lift points, but I'll check.
 
kustomizingkid said:
I don't believe for 1 second that the car is flooding... efi cars don't flood...
Click to expand...

The only way it even tries to catch and run is with WOT (injectors off) or if you crank it cold with the fuel pump inertia switch tripped off and it runs for a couple seconds on the residual fuel in the system. If you just crank it with the pump on, threre is an overwhelming smell of gasoline and if you remove the plugs they are wet with fuel. Take them out and dry them and blow out the cylinders and you can repeat the process all over again, but it eventually floods out. Something's obviously not performing correctly or the EFI would control a flooding situation. I'm no expert, but those are the symptoms.
 
Tiltedhalo said:
Ok, long shot. What type of fuel injectors? some one could have replaced the stock injectors with high impedance EV6's with pig tails. The ECM will slam them wide and fry.
Click to expand...

I suppose, though there's no evidence of anything other than stock wiring, and these are the exact injectors and regulators that were on the car when it was running and I drove it onto the lift under its own power. Literally everything is original to the car except for what was essentially a running (at least we were told) long block from a salvage yard.
 
Does anyone find it odd that I can't feel any vacuum at the vacuum ports on the intake while cranking? Even though Frogman says that fuel pressure regulators don't need vacuum to start, it seems like so many things run off of a vacuum that it has to have some impact on other systems. I claim total ignorance on this point because I don't know how these engines are supposed to behave while cranking. I tried a SOHC 4.6 in a '95 Town Car and there was noticable vacuum while cranking.
 
You must log in or register to reply here.

Members online

Total: 85 (members: 1, guests: 84)
Back
Top