Alfa Romeo Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter #1
Happy new year, all!

The Backstory:
I pulled an 87 Milano Verde out of a cornfield in Iowa in 2016. Since that point, I've been slowly working my way through the car getting it road worthy with an abundance of help from community members. I'm getting dangerously close to getting another Milano on the road. Although not a complete list, some of the work that's been done so far:
  • complete suspension rebuild, front and rear
  • rebuilt transaxle
  • new clutch
  • new slave cylinder
  • new exhaust (all sections)
  • new driveshaft flex discs
  • new steering rack
  • new CV boots
  • rebuilt and repacked wheel bearings, front and rear
  • rebuilt CV joints
  • new (OEM) exhaust headers
  • new plugs and wires
  • new big intake and plenum couplers
  • new (old stock) fuel tank
  • new fuel pump
  • new post-pump fuel filter
  • relocated pre-pump fuel filter (removed in-tank filter and installed high-flow filter before pump)
  • fuel injectors serviced
I'm going to finish this car this year. Hopefully earlier than later. I wanted to get a post up with all the facts, assumptions, and potential next steps and ask the community for help.

Where we're at:
The car starts and idles very well, both hot and cold.
  • Without load (cold), the engine revs freely, but stumbles and backfires occasionally at higher RPM.
  • Without load (hot), the engine begins to stumble with any throttle, with backfires. It does not die when coming back down to idle, though.
  • Under load (cold), it drives alright, but feels very down on power if you get on the accelerator.
  • Under load (hot), it begins to cut out with ANY accelerator. This happens abruptly, like a fuel map has changed, or some system went from cold to hot.
What we've done recently:
  • New fuel tank, visually inspected and appeared rust free.
  • New fuel pump (recommended from the 87 part list).
  • New fuel filter (high pressure, post-pump, OEM).
  • New fuel filter (pre-pump aftermarket high-flow. replaces in-tank filter)
  • New (old) distributor.
  • New wires (correct OEM set).
  • New big air intake hose to plenum.
  • 6 new plenum coupler hoses.
  • New spark plugs.
  • New AAV (2 years ago now, but was new and tested then)
  • Confirmed correct timing (+7, although seems to like about +11 better here in Portland).
Considerations:
1) When chasing down the ignition issues, I purchased a distributor off eBay that appeared to be mechanically sound, but must have been rebuilt wrong. When starting, the engine backfired and blew the plenum off the intake coupler hoses. I replaced these after this event.

2) When doing the fuel work, I pulled the line after the pump after a few engine cycles to confirm clean fuel. It appeared visually acceptable, but I keep thinking there might have been some dirty fuel in the lines that may have worked back into the filters. I'm not sure if I'm being really paranoid about this.

Theories:
1) Just about the only thing I haven't been able to confirm with a measurement is fuel pressure. It seems plausible to me that the problems described are fuel pressure related, especially considering the somewhat uniform loss of engine power, although it's much more apparent when hot (maybe the map leans out when hot?). The fuel pressure regulator is one of the only parts I have NOT replaced yet. I know you said they don't traditionally go. I supposed the best next step is actually measuring fuel pressure, which leads to a few questions I'd like to ask you:

  • Where is the best place to do this? The fuel rail doesn't have a port on it.
  • And what should the reading be if healthy?
2) This is maybe more of a stretch, but it's worth mentioning. I've had an opinion that the cause of the issues might be bad injector seals. I replaced those when I had the fuel injectors serviced last year, so they were new at that point. I'm not sure if the big backfire could have unseated or destroyed anything. They appear visually ok, as far as I can tell, but I really don't know if that's even diagnosable visually.

I sincerely appreciate the community help and can't wait to get this one on the road.
 

·
Registered
Joined
·
3,347 Posts
Lots of progress! If you pull the hose to the cold start injector you can plumb in a fuel pressure gauge inline. It's been a while but I think somewhere around 36 PSI is about right. Here's a pic of what I did on mine when I had it.

Kevin

VerdeFuelPressureGauge.jpg
 

·
Registered
Joined
·
38 Posts
You've done a lot of good work. I would like to know where you found a steering rack as I cannot find one. Thank you.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #4
You've done a lot of good work. I would like to know where you found a steering rack as I cannot find one. Thank you.
I had the good fortune of having a bunch of spare parts in the trunk when I bought the car, including clutch and steering rack. I've had good luck getting hard-to-source parts from the marketplace forum on this site. You might also call Centerline or APE and see if anyone has a lead on one.
 

·
Registered
Joined
·
1,068 Posts
~36 PSI is correct. Plumbed to the CSI is a good spot as Kevin suggested
 

·
Registered
Joined
·
28 Posts
Discussion Starter #6
Alright! I've got a quality gauge plumbed in near the 7th injector. It shows ~26 PSI and holds steady. So... progress.

Now the question becomes:

is this a product of the fuel pressure regulator? or is the problem downstream somewhere? I've replaced the fuel pump (twice) and it currently has the 87 spec pump, which is a slightly higher throughput.
 

·
Registered
Joined
·
3,347 Posts
So 26 PSI instead of 36? Were the pumps you put in there new or known good ones? Have you changed the in line fuel filter? If it is clogged that could cause low pressure, if not that then as you suggest I'd check the fuel pressure regulator.
 

·
Registered
Joined
·
28 Posts
Discussion Starter #8
I took more measurements this morning.

With vacuum line disconnected, fuel pressure is ~40 psi.
With vacuum line connected (line replaced with silicon line along with all other intake lines last year) ~26 psi at idle.

When revving the engine (no load, vacuum connected), the pressure briefly spikes at ~40 psi before falling to around ~24 psi. The engine stumbles while the pressure is high.

Fuel pump and filter were new last year when trying to recover from a rusty tank (replaced after new tank went in).

Based on the ~40 psi when vacuum is disconnected, I believe the pump/filter are fine. These signs seem to point to the pressure regulator failing. Do you agree?
 

·
Registered
Joined
·
28 Posts
Discussion Starter #10
Installed a new pressure regulator today. Things seems drastically better:
  • Significantly less cranks to cold start
  • Revs climb much faster and more linear
  • No backfire when coming off throttle
  • No noticeable power loss or engine hesitation under any condition (cold/hot, loaded/unloaded)
It certainly feels like a different car. Probably closer to "right." I've never had the pleasure of driving one that is "right," so it hard for me to comment.

I only had time for a short drive around the block after installation, so I'm hesitant to declare victory. During that short drive, power seemed to come very linearly. I climbed to ~5000 in first before my straight ran out. It seems happiest between ~3000 and ~5000. Does that sound right?

It still has a slight stumble at idle when hot. Not enough to kill it, but a little lumpy. I imagine a few cycles of idle adjustment/timing will take care of that.

Things are encouraging. Next step is a little longer driver with room to get up to speed. I'm definitely nervous about that one. Never had the Milano more than a mile from home. Fingers crossed.
 

·
Registered
Joined
·
3,347 Posts
Nice! 3-5K sounds right. Hard to say if the slight stumble at idle is normal or not, these cars aren't the smoothest idlers. Go for a nice drive!
 
1 - 11 of 11 Posts
Top