I bought a 91 vert Tuesday for 900 dollars and the body was in great shape. I drove it around and the oil pressure stays where it should and the temp doesn't move. I checked for bubbles in the coolant and rev'd it 4,000rpm to watch for smoke when it warmed up.

I was on my way to work yesterday and it acted like it wasn't getting fuel for a few seconds and then was fine. A minute or two later it falls on its face and dies as I pull off in to a parking lot. First thought was blown EGI fuse or the fuel pump went out/relay went bad.

Everything was fine. I hotwired the fuel pump to make sure it was working and it is. I pulled the spark plugs and the front had fuel but the rear were dry. I took the intake tube off and sprayed starting fluid and it would start back up but die as soon as I stopped spraying it. Without the starting fluid it will just crank and crank and once in a while it will act like it will start, hit 1,000rpm and then die.

I'm lost, really. I checked the compression and it is fine. With a piston engine compression tester I get three even bounces to 85-90psi on all six faces.
Checking the injectors as soon as it stops raining and that's really all I can think of.

 

Check the AFM connector. If that works its way loose the car won't run. After that, vacuum leaks, timing.

 

I thought that if the MAF was disconnected that the car would still start but it would be in limp mode.

 

Update: I pulled the intake off to check to make sure the injectors were firing. The primary injectors weren't and I discovered a bad ground (the ecu ground) and fixed it. The bolt was really loose and there is a chance that it was messed up when I tried to remove the intake. It was grounded on the bracket that has the rats nest plugs attached to it.
They are firing now and I'm hoping to get all back together and see if it will start now.

 

Wouldn't start so I took the intake off again and made sure there weren't any vacuum leaks. I did find that the water pump thermosensor was unplugged, plugged it in and it started up but died. I started looking over the engine and trying to figure something out. I unplugged the MAF and it started and idled fine.

It ran really bad and black smoked from where it was running rich. As soon as I plug the MAF back in it dies. The REF voltage stays the same with or without it plugged in. The ground wires are good. The ecu wires have .25 volts on them. I did a resistance test on the MAF and it only passed one of the tests. However, I couldn't find a resistance test for the 5 pin MAF. The FSM only shows one for the 7 pin AFM/MAF? It is a n350 ecu/MAF.

Does anyone have any ideas on where I should start or if I should go ahead and replace my MAF? I just don't want to spend 80 dollars on a used MAF only to find out it isn't the problem.

 

Are you sure you have no vac leaks? It really sounds like it's getting too much unmetered air.

 

I'm going take the intake apart one more time and replace any questionable vacuum lines. I'd rather spend 10 dollars on vacuum hose and a few hours of time than to waste money on unneeded parts.

I sprayed Starting fluid all over to try and find a leak and never did.

 

did you check for fuel?...to see if you are getting any at the engine?..it sounds like a filter problem.

 

Yes, I pulled the primary fuel rail off and cranked the car. It is getting fuel.

 

The pump could be weak, or your pressure could be too low. You ave a way to test fuel pressure?

 

A couple of things:

The AFM problems tell you one of two things, either the AFM is bad or you have a major vacuum leak. The car could be getting air that that AFM isn't compensating for with fuel.

The intake gaskets and injectors are the most common places for vacuum leaks so seal them carefully.

 

I'm going to go ahead and replace the MAF with a new/used one and see if it helps. It really seems to be the only thing left. I pulled the intake off again and made sure everything was sealed and hooked up correctly. It still did the same thing. Would act like it was going start, rpm hits 1,000, and then dies; with the MAF hooked up. Without it hooked up it will idle at 700-1000 and black smoke.

 

Updating before I run to work.
I replaced the MAF and it didn't help at all. I pulled all of the intake off and double checked every line. It is getting fuel and spark.
I'm completely stumped and am going to take a break from fixing it to put a clutch in my civic.
If anyone has anything that they think is worth testing/checking please tell me.

 

The fuel sock on the intake of your fuel pump, replace that.

The fuel sock is one of the most neglected items on the car, and yes, they clog up.

 

You should check for codes, cant hurt and its quick to do.

1300cc, 2nd gen code checking

 

It has a new fuel sock and it never threw an engine code. Ill check then when I get home but I remember thinking it was weird that it died without throwing a code.

 

Hey if you haven't changed the spark plugs i recommend you start there, i had same issue and once changed fixed all my problems. They seem to have spark but the fuel can fowl it out if its not enough spark.

 

I actually did change out the spark plugs and it didn't help at all.

I am making a check list of things that I need to check/test this weekend. I'm really not sure what can cause a car not to start when it has spark, fuel, air, and compression.

Any suggestions would be great. I'm really hoping to have it running again by the memorial day weekend.

 

Bump. Bought all new soft lines, a fuel filter, and a few other odds and ends to make sure I have no vacuum leaks. Hopefully it will start tomorrow.

On another note; is there anything that would prevent an automatic vehicle from starting when it has spark,fuel,air, and compression? I mean, I've never worked on an automatic and I was wondering if there was a fail-safe to where it would cut-off everything as soon as it detected the car starting?

I'm utterly confused as to how a car with everything it needs to start, won't start.

 

The Inhibitor Switch on the auto would prevent the car from turning over thus it wouldn't allow the starter to work. The ECU should have 12 volts w/key to on at pin 1R (S5) if the car were in gear otherwise it would have rather low voltage when in park or neutral. If you're getting all the necessary ingredients to start the car then it is doubtful that pin 3D is the cause for the car not to start.

Pin 1U is the A/T Switch and it should read 0 volts w/key to on.

 

Yeah, it is getting everything necessary to start. I am just getting desperate.

Is there anyway that a 90-95psi reading on all six faces (cold) would still be too low for the car to start?

 

If you just bought it, how do you know the sock in the tank is good?

 

Lol, because 5 out of 7 fcs I've had needed the fuel pump replaced or the relay was bad. So the first thing I did whenever the car died was pull the pump. It is new, it is working, and the sock is brand new as well. Also, I went ahead and replaced the pump and sock with a new one.

I'm pretty close to just going ahead and pulling the engine. At this point I can only assume that it has some weird issue where 90psi isn't enough compression for it to start.

 

replace the AFM, done.

it's kind of rare to have an S5 AFM go bad but it could happen. i've had this same scenario on numerous S4's which had bad airflow meters, injectors and ignition stop firing with a faulty AFM plugged in but will run without it.

 

Sorry, thought I had posted before that I did buy another s5 afm and it didn't change it at all. I'm stumped.