Engine Help hard/no start runs rough.

[Mr.Kelley]

I'm running an 89 5.0 with Explorer intake and efi in a 62 Falcon. I have to give it either to start. It runs rough and backfires when cold. Once warm it runs ok but the idle will sometimes settle at 1500 to 2000 rpm and it surges like a fuel starved carb above 4500rpm. It doesn’t have any codes that are unexpected. No emmisions are installed. Codes...81,82,85. I also have a 15, ecu memory voltage loss, but I have a master kill switch for anti theft and drag racing. Problem started over the Summer. I got it hot 230 coming home from work one day. I put a better electric fan on it and thought I was good. After the runnig hot was solved it would surge at above 4500. I checked my fuel pressure regulator and found I could only get 45psi if I cranked up the pressure. It would run at 60 when I first installed the efi, thus the adjustable regulator. I put a new pump pickup guage assembly in and it is adjusted to 38psi. Problem still persisted. It fried a pertronix flame thrower coil so I replaced it with a Bosch wich lasted all of an hour run time. I read here that TFI and PIP problems can kill coils so I got a new distributor along with plugs and wires and a new foxbody coil. I've thrown alot of parts at it trying to fix it. I've gone through the idle surge checklist and all checks ok. Compression is good. I was thinking injector(s) but have no way to test other than the long screwdriver against the ear.

 

[limp]

The mechanical stethoscope at HF is cheap and works well.....

 

[AeroCoupe]

So it sounds like you have fuel. With regards to ignition are you sure you have it timed right?

 

[Noobz347]

Setup a temporary method of mentoring input voltage to the coil.

A couple of bite connectors, two wires, and a cheapo 12v automotive gauge should do.

 

[Mr.Kelley]

Thanks for replying on Christmas eve. I have to charge the battery. I'll check the timing when I get it started. What should it be.

 

[Noobz347]

With the engine running you should have 12.4ish to 12.9ish voltage at the coil.

 

[General karthief]

I am suspicious of a vacuum leak, prolly at the intake/head gasket, got a vacuum gauge?
Just a guess but I think every EFI issue is vacuum related
Got good charging voltage readings?
Coil grounded good, using the fox bracket?
Just spit balling here, what's fuel pressure at 3500+ RPMs?

 

[Mr.Kelley]

Got it running let it warm up pulled fresh codes, (KOEO81,82,85,15. KOER94,44) air air injection delete normal. 15 because Kill Switch

checked timing, 14bdc spout unplugged. Spout in 20ish at idle around 35 total

fuel pressure, 38psi @3500

No obvious vacuum leaks.

 

[General karthief]

Got a vacuum gauge you can use?

 

[Mcmahst]

I agree with the general, those engine are notoriously vacuum leakers. Don’t ask me how I know.

 

[Mr.Kelley]

So your saying I might have a vacuum leak between the intake side of the head and the intake lower in the lifter valley. How would I check that. Pull the intake and look for telltales on the gasket. More important how do I fix it.

 

[mikestang63]

make or buy a cheap smoke machine and check for vacuum leaks. You can also spray around the intake, throttle body with BrakeKleen for leaks- if the rpm increases you found the leak. also when is the last time you changed the fuel filter.

 

[limp]

An UNLIT propane torch does a good job too... Move it around the intake area, if your RPM increases you have a vacuum leak..

 

[Mcmahst]

I’m not saying for sure, but if this site got a dollar for everyone who created almost the same post: runs like crap, low or too high fuel pressure, and it turns out to be one or more vacuum leaks, this site would be rich.

It’s just the most common root problem with 87-93 5.0 Mustangs. So, what is the vacuum reading at idle, and at 3500rpm? Same for fuel pressure. Check that and get back to us.

 

[General karthief]

I suspected a vacuum leak mostly because of the 'ran hot' statement, going back to the first post to refresh, 230* is hot but not excessively overheating, check the torque on the lower intake bolts, got O2 sensors? Didn't see any codes for them so I'm guessing yes.
Has the computer ever been checked out?
I'm concerned about the coil failures, the 'Flame Throw-Away-er' is understandable but losing a second coil right after is troubling.

 

[Noobz347]

I’m not saying for sure, but if this site got a dollar for everyone who created almost the same post: runs like crap, low or too high fuel pressure, and it turns out to be one or more vacuum leaks, this site would be rich.

It’s just the most common root problem with 87-93 5.0 Mustangs. So, what is the vacuum reading at idle, and at 3500rpm? Same for fuel pressure. Check that and get back to us.

I would hazard to guess that 90% or more of all engine and electric issues can re resolved by understanding and running one or both of these checklists, from top to bottom:

• Cranks but No Start Checklist - jrichker
• Surging Idle Checklist - JRichker

I am very aware that technical savvy differs between folks but that where the Old Guys and Mechanics can help the most. I love to see threads and discussions that talk about how to perform these tests, the the info you get from them, what it means, and what to do next.

That's why it's good to be nice to the new guys, even if they're a little cocky. They probably don't know squat. If we can help them understand how to do the items above then narrowing down the issues becomes a snap. Understand the checklist and you then possess the vocabulary to ask questions at a minimum.

But wait! There's a bonus! Finish the checklist and you know how to use the tools in it. Seriously, it's the Cliff-Notes/cheat version of troubleshooting a Windsor Mustang.

@jrichker

 

[manicmechanic007]

There are a few ways to test injectors
One easy way is with a spare injector connector you wire up with a trunk release switch (momentary switch)
Apply power and ground to the injector while you watch the fuel pressure drop using the switch
Easy to hear them click as well with the key off
Make sure they all have roughly 8 to 18 ohms
Get fancy and test fire them with injector cleaner if you see or hear any differences in the injectors operation

 

[SeaCorey]

I would hazard to guess that 90% or more of all engine and electric issues can re resolved by understanding and running one or both of these checklists, from top to bottom:

• Cranks but No Start Checklist - jrichker
• Surging Idle Checklist - JRichker

I am very aware that technical savvy differs between folks but that where the Old Guys and Mechanics can help the most. I love to see threads and discussions that talk about how to perform these tests, the the info you get from them, what it means, and what to do next.

That's why it's good to be nice to the new guys, even if they're a little cocky. They probably don't know squat. If we can help them understand how to do the items above then narrowing down the issues becomes a snap. Understand the checklist and you then possess the vocabulary to ask questions at a minimum.

But wait! There's a bonus! Finish the checklist and you know how to use the tools in it. Seriously, it's the Cliff-Notes/cheat version of troubleshooting a Windsor Mustang.

@jrichker

As a perennial new guy in here for like two decades..., I want to thank you more experienced guys for the knowledge, wisdom, and patience.
Happy New Beer!

 

[Praetorious]

Don't mean to hijack but on the subject of testing injectors, about 6 months ago I saw a video of someone using one of those old EECIV monitors and after that I just had to have one! ( I'm weird like that)

I found a lady in Long Beach thru craiglist that had one hardly used if ever, she even threw in the proper overlay for my 89/91 , man those machines are the bees knees.

You can watch your injectors in real time opening and closing, rev it up a bit and you have yourself a killer light show watching those things fire on and off a million miles a second,lol.

You can test all your sensors like you ACT and ECT in real time as you drive, we always think those sensors are bad but with the machine you can really tell for sure if they are working or not,the machine might be primitive but it was made for our cars and anything else of the time period, I love it.

 

[Mr.Kelley]

After more checking, completing the 2 checklists and coming up inconclusive, I'm going to pull the manifold. Hope to find a vacuum cap missing on one of the hidden ports bottom side of the upper half.