Alfa Romeo Forums banner

1 - 16 of 16 Posts

·
Registered
Joined
·
25 Posts
Discussion Starter · #1 ·
'85 Spider Veloce:
Has been garaged for about the last 15 years. 43k original miles. We're bringing her back to her original beauty and fierce running 4 cylinder.
What we've done so far:
Changed all consumable elements - hoses, belts, fluids (oil, diff, trans, brake, coolant) plugs, wires, coil, rotor & cap, flywheel position sensors, O2 sensor, engine and trans mounts.
Changed out both fuel pumps and filters.
She now runs great - for about 10 -15 minutes. Then at higher revs she starts to run rich. I can start to smell gas fumes, she starts to choke out and loose RPM's and power and chugs to a stop. I can usually wait about 10 minutes and it will run well again till it repeats the problem all over again.
I thought it may be the air/fuel adjuster (black box on top of the air cleaner). So I watched a bunch of videos on cleaning and making adjustments to the small cog wheel. I marked where I started and moved the wheel about 8 cog "teeth" to clockwise (to lean it out a bit). This didn't work.
I'm really at a loss as to what to try next.
Any suggestions would be greatly appreciated.
Thanks all.
 

·
Premium Member
Joined
·
1,639 Posts
I would first put that back in the position it was in before you moved it.
It could be that your TTS is not telling the CSI to stop spraying fuel. I would check that.
I assume that you verified that the return fuel line from the pressure regulator is clear and not clogged and that the regulator is functioning okay. Air filter is clean? nothing blocking the air flow before or after it?
Is the O2 sensor correct and is the signal getting back to the ECU?
Have you tried going through the L-Jetronic troubleshooting guide that is on this forum?
 

·
Administrator
Joined
·
17,779 Posts
A link to the Spider L-jetronic Diagnosis Guide is in my signature. You may need to click the down arrow to see the whole signature.

Fiddling with the AFM is the last thing I'd suggest. (It is good you marked the original position.)

Is the O2 sensor old? Does the catalytic converter get very hot?

Buy, borrow or steal a fuel pressure gauge. The FI system is expecting a specific fuel pressure. There are some fuel pumps that fit but put out too much pressure. The Fuel Pressure Regulator cannot cope with pressures that are way out of range. A quick test for faulty FPR is to remove the small vacuum hose and check for the presence of raw gas (sniff, wetness). There should not be any gas on the vacuum side of the FPR.

2.3 bar is ~ 33 psi, 2.7 bar is ~ 39 psi
1678781

1678782
 

·
But Mad North-Northwest
Joined
·
11,639 Posts
I thought it may be the air/fuel adjuster (black box on top of the air cleaner). So I watched a bunch of videos on cleaning and making adjustments to the small cog wheel. I marked where I started and moved the wheel about 8 cog "teeth" to clockwise (to lean it out a bit). This didn't work.
Like the guys said, you should put that back. Messing with the AFM is the last thing you should do, and only then if you really know what you're doing.

One quick thing to check is to pull the small vacuum line to the fuel pressure regulator. If there's any fuel or wetness there you've found your problem.

Beyond that, go through the entire L-Jetronic guide in Eric's sig. If I had to guess from your symptoms I'd say it's a bad coolant temperature sensor (CTS), a bad fuel pressure regulator (FPR), or a bad oxygen sensor. But go through the whole guide.

Don't mess with the TTS/CSI, that's not your problem...they're only powered when cranking.
 

·
Registered
Joined
·
25 Posts
Discussion Starter · #5 ·
Thanks guys.

I replaced the Air / Fuel cog back to original and sealed it back up.

I'm going to swap the FPR and the coolant temp sensor. And also test the O2 sensor (just replaced).

I'm also going to test the pressure coming off the replacement Fuel pump and ensure it's in spec range.

And I'll report back the results.

Thanks guys - as always you (collectively) are a huge help.
 

·
Premium Member
Joined
·
1,639 Posts
Don't mess with the TTS/CSI, that's not your problem...they're only powered when cranking.
[/QUOTE]

Gubi, I was thinking that you were FOS regarding the CSI as I always assumed(key word there) the CSI would stay on via the TTS until a temperature was reached but I actually went out and tested on one of the cars here yesterday and it only gets voltage during cranking like you said.
Thanks for the education. :)
 
  • Like
Reactions: Gubi

·
Registered
Joined
·
9,416 Posts
test the pressure first before throwing money at a new FPR - and if you do get a new FPR, then get a Bosch.
Be careful removing it, if the nut is stuck, you can end up twisting the whole contraption out of shape.
 

·
Premium Member
Joined
·
1,639 Posts
I get that a lot :LOL:
:LOL: Me too but I try to verify before I open my mouth. Try being the operative word.;)
And just because I am correct on one thing doesn't mean I am not FOS on something else!:LOL:
 

·
But Mad North-Northwest
Joined
·
11,639 Posts
From what I've seen the FPR typically fails by leaking fuel into the vacuum line rather than by providing the wrong pressure. This makes the engine run really rich.
 

·
Premium Member
Joined
·
1,639 Posts
From what I've seen the FPR typically fails by leaking fuel into the vacuum line rather than by providing the wrong pressure. This makes the engine run really rich.
Should I agree with you?😂
 

·
Registered
1982 Alfa Romeo Spider Veloce, 1997 BMW M 3/4/5, 2007 Land Cruiser
Joined
·
53 Posts
Until I sorted it out, my car would pull a vacuum on the gas tank until it stopped running. I’d crack the cap, hear a hiss, and it would crank right back up. Yours appears to run rich first, but nonetheless, insure you aren’t pulling a vacuum. Did it worse when fuel level was low.
 

·
Registered
Joined
·
9,416 Posts
although if the FPR is leaking raw fuel into the vacuum line, it is toast and won't be holding the correct pressure....the diaphram has bust.
great photo from BB (probably even yours, Tom? or was it Eric...or...oh well thanks whoever:))
1616356369000.jpeg
 

·
Registered
Joined
·
1,109 Posts
Testing fuel pressure and tank venting and FPR and clogged cat. conv. are all good ideas. FYI, I have had positive results adjusting the AFM on these older cars. I believe that the clock spring looses tension over time and the vane swings too far. 2-4 notches tighter leans the mixture a bit. In many cases the engine runs better, crisper throttle response, cleaner spark plugs, better mpg, etc. Try it. No need to reseal the plastic top, it will stay in place.
 
1 - 16 of 16 Posts
Top