Bad FPR?

[3vilE30]

Hello all. I'm having a bit of trouble getting the M20 running right.
I followed Bentleys procedures for various tests. Getting a Code 1222.

So far I've narrowed it down to fuel issues.
I setup a fuel pressure tester and my results are a bit weird.

Pressure Tester T'd into the main fuel line going into the rail.


Cold start after a few days M20 runs like garbage sorta holding a 600-500 rpm idle



Cold again with the FPR vacuum line unplugged and the vacuum port on the intake plugged as best as I could. Pressure is around 40-42psi but it looks like its struggling, M20 runs worse.



Fuel Pump jumped FPR vacuum line connected getting correct fuel pressure.



Closed Loop test engine warm FPR connected idles sorta good but low around 600-500 with a cel



The problem is sometimes rail pressure holds, sometimes it doesn't more noticeable that it holds pressure when there is some heat in the engine. Which gives me inconclusive data as to if the injectors are leaking or not. I know the FPR is bad, but I'm trying to rule out leaky injectors or a bad fuel pump as well.

Also when I tried to slowly clamp off the return line per Bentley's instructions Pressure does not go up. There is no fuel in the FPR vacuum line either.

The only time the m20 runs smooth is when I removed the fuel pump relay and for like a solid 10 seconds it idles smooth and runs like a normal m20.

[3vilE30]

And it looks like the videos didn't link correctly...

https://youtu.be/ipdorJGDLC0

https://youtu.be/VZhVDVq0yb0

https://youtu.be/XcBUMzEaotE

https://youtu.be/iML-x-XWV3w

Forgot to add its an 87 325iS

[e30davie]

If you know the FPR is bad, just replace it, then move on to the next thing. Takes all of 5mins to swap it and surely you can grab a second hand one from somewhere if only to test your theory.

The golden rules of trouble shooting are fix known problems first, and only change one thing at a time.

The other thing is, do you know the history of the fuel pump? cause for the price of them it might be good insurance just to put a new one in if you intend to keep the car a while.

[3vilE30]

I realized I should have titled the thread better.
Going to order a new FPR and see if that fixes it.
Fuel Pump was "new" as stated by the previous owner, but it was only to mask a dead in-tank fuel pump. So it's been pretty stressed, I replaced the in-tank pump with a new low pressure pump, external pump sounds alot better now as for performance it shot up rail pressure to the correct psi so it seems okay.

[e30davie]

Does the fuel pressure drop when you give the throttle a stab (ie vacuum goes to zero) and then does it come back to ~42psi or so quickly?

[3vilE30]

Idles around 35psi then dips to 31 when throttle is applied but breifly shoots up to ~42 psi then back to ~35ish psi idle

[Kershaw]

1222 is such a broad code it might as well be useless. I would replace the fuel relay, then the injectors, then replace the FPR, then the fuel pump and filter.

[3vilE30]

Replaced Relay = No change
injectors are low milage 19lbs bosch injectors
New Fuel pump on the way went with a TRE-507
New FPR on the way.
Going to replace the distributor, rotor and plugs in the process. Ill report back when I install them.

[packratbimmer]

You need a chip to run 19# injectors

[squidmaster]

You don't NEED a chip to run 19lb injectors, the ECU can correct with a good o2 sensor. Though the car will not run correctly and it may have skewed AFR numbers, especially at WOT, it won't have the effect he's describing about the pressure. Check for leaks/bad lines, replace the FPR (since you already are), and see if that fixes the problem first. Then I would probably replace the fuel filter next. If you're sure the fuel pump is new, it might not be a bad idea to at least check the connections and hoses on it.

Checking your injectors is free and pretty easy, relatively.

https://www.youtube.com/watch?v=Sfq-fM3-TIk

https://www.youtube.com/watch?v=8rk0tKtiVic

If you're using the 19lb yellow body ford injectors, they are NOTORIOUS for breaking down. I always order 1 or 2 extra when I buy a set, because it seems about 30% of the time at least one injector is bad.

[3vilE30]

I ran 19lbers without a chip for a little, drove the same idle a bit better but as squidmaster said the AFR's might be tweaked. Currently have a mark d chip

They are f6ve-a5a injectors off of a Ford, forgot which model.
I hope you aren't talking about those! Luckily I have 2 spares.
I don't think the injectors are a factor. I pulled the plugs after letting the motor run for a bit and sit. Pulled the plugs and none of them were wet, if anything Ill swap in the stock injectors if everything else fails.

I knew I forgot to check something, forgot to check voltage at the in-tank and inline pumps.

Parts are schedueld to arrive on friday. I haven't driven this thing in a while one problem after another.

[3vilE30]

Well damn,
Tossed in the new FPR - no change
New Fuel Filter - no change
New TRE Fuel Pump - no change

I swapped in a new distributor rotor and cap just cause idk how old the ones on the car were. - no change

Last resort I put in the stock injectors back in and bam.
I didn't have time to drive it around but no pissing out the tail pipe
Idled consistently and best part NO DAMN CEL
YAAAAAAAAAAAAY
I let it idle for a solid 20 minutes.

With the 19lbs injectors it gave me a cel in less than 5 minutes of idling and thats if it actually idled.

Kinda mad that I bought the fuel pump and fpr but oh well, its my bad for not swapping in the old injectors. In the Bently everything pointed to a bad fpr.
But I see it as making the car more reliable.

[packratbimmer]

Glad to hear you figured it out. My car fouled the plugs very quickly with 19# injectors - it was completely stock. MPGs suffered as well.

I do a lot of cold starts and short trips (unfortunately) so that makes a difference.

Make sure your oxygen sensor is working now that you have the situation under control .

[Kershaw]

1222 is such a broad code it might as well be useless. I would replace the fuel relay, then the injectors, then replace the FPR, then the fuel pump and filter.

What did I say?

I'm glad you figured it out eventually.

[3vilE30]

What did I say?

I'm glad you figured it out eventually.

Thanks man!! I should listened.
I genuinely thought it was the FPR or the fuel pump as suggested by another e30 guru. But when I thought about it everything happened after I did the valve cover to throttle body hose and I pulled the rail for this. I think the injectors didn't seat right into the head. All the plugs looked fine before I pulled the rail but now they are just carbon fowled from running rich/lean
I pulled the plugs and they were dry so I didn't think it was the injectors. I should have done some further tests but the issue only happened at idle plus I just REALLY HATE PULLING THE FUEL RAIL.

Im going to get the 19lbs injectors tested and see what's up with them.

On another note I bought a fuel pressure regulator from rock auto it was the beck and arnley one. I usually do not have an issue with rock auto but to make sure I got the correct FPR I checked rail pressure and it was at 30psi on idle and it sat at the 2.5 bar mark with the vacuum line disconnected soo yeah. It ran like normal surprisingly. I put the old 3 bar bosch fpr back in going to return this. Also I noticed that the 2.5 bar starts up a hint sooner than the 3.0 bar fpr. I think the TRE 507 doesn't have check valve and it leaks down rail pressure since the OEM pump I had in there held pressure.