Running rich - post sticky help pls

[71Squarenstein]

Hey everyone,

I did some searching on the prob I am having, and have some questions.

I have a 71 Squareback FI, and I am pretty sure it is running rich and at idle (not every time, but the odd time) it gives me one or two 'air pops' out the exhause every 10-15 seconds. I read some tips on here to check some things, but I have questions:

1. Check the alternator voltage - If my alternator is pushing within limits (13.2-14.4 (if I remember??)) is it possible it could also be losing voltage AFTER the alternator terminals, causing the FI problem? Is there a closer terminal port I can check from to get an accurate FI voltage/amperage?

2. Some people mentioned exhaust leak. I don't really smell any fumes inside, but 'hand over the tailpipe' test tells me it is rich. My deck seal is fine and I only have a couple SMALL pan holes, but like I mentioned, no detectable fumes or anything like that. Replaced my fuel line under the car and refit a new gas filler hose, so the lines should be ok. I checked the heater boxes and the outer 'insulation' looking covering is deteriorated to the point I can see some kind of 'wire mesh' or something.. does this make sense? could this be contributing to the popping?

3. I started reading the sticky, but 63 pages was a good dose to sift through. Pardon me if I am not a FI guy instead of a carb guy, but is there a way to change the mixture on the FI? OR should I be looking at all the ancillary things (points, iginition, etc etc)? It idles well without jumping or gaps or anything, just this odd popping once and a while..

any help is appreciated! Thanks in advance!

[Mike Fisher]

The Bentley Manual gives complete instructions on everything Type 3. I bought mine at books4cars.com. We were all LOST before we got the Manual? PS WELCOME!

[LesTroyer]

biggest thing with the D-Jet FI is vacume leaks. I'd check for leaks and make sure the Fuel Pressure is set at 28lbs

LEs
_________________
Thanks

Les

1972 Fasty -- more or less stock (1600, FI...)
1971 Square
1966 Fasty body on IRS pan --

[KTPhil]

D-Jet uses manifold vacuum as the primary indicator of engine load and enrighening needs. Less vacuum implies full throttle, high load, and need for enrichment. So if you have a vacuum leak, you fool the computer (ECU) into enrichening it when it isn't needed. Just because a hose looks good doesn't mean it isn't leaking. Just replace them all.

Next, and much less common, is a defect in a temp sensor or wire leading to one of the two, and the high resistance implies cold temps and need for enrichment. Bentley and the sticky give correct measurements.

Last, poor fuel pressure can make it smell rich but also be lean at times. You need a steady 30 psi, measureable with an ordinary water pressure gauge at Home Depot and some hose connections.

[71Squarenstein]

Thanks for the suggestions guys!!! Sorry if the follow ups are kindof newbish, learning as I go with this thing..

With the vacuum leak, is there a tool to see what the vaccum is currently at? Does the water pressure gauge work for this as well? I just would like to be specific instead of spending all the money and time on replacing all the cables if it is only a couple of them giving me the problem..

Will give the temp sensor a shot as well, do you mean just the general engine temp (sensor)?

With the water sensor / fuel pressure issue, I assume I just hook the water pressure gauge up inline with a part of the fuel line (say, the long line running right up to the engine before it attaches on the manifold (?)

Once again, thanks for all your help! Hopefully I will get to the bottom of this soon!

[KTPhil]

You need a Bentley or other repair manual, but as to your questions...

No gauge will tell about vacuum leaks. Just replave all the cloth/rubber hoses in the engine bay, and you won't have to worry about it. If one is bad, the others will soon follow anyway. Do both the fuel and air hoses while you are at it.

There are two temp sensors. You have to disconnect the wires(s) and check them with a VOM, noting the ambient temperature. Do this before starting the car.

What makes you think it is running rich?

[71Squarenstein]

KTPhil,

Well, the 'air popping' in the exhaust happens - and by what I was researching on the forums was partially due to this reason (running rich). I was told to check by covering the tailpipe with your hand and then sniffing it (no, not to get high lol) and by what I know normal exhaust to smell like, it seems really rich in gas smell. I mean, I could be wrong, but every time I stand behind the car, it just smells too much like gas coming out.

As a last measure, not to accurate though, for a 1600cc engine, it seems to me that it should be getting WAY better gas mileage than my old 2005 Mazda v6, but that probably is terribly subjective to many factors, so I don't really go by that.

I purchased the Haynes manual, but by what everyone says on these forums, they seem to unanimously agree that the haynes one is crap compared to the Bentley manual. Will have to go grab that bad boy.

Man, it sucks how expensive hoses are here - I was hoping you guys wouldn't stick to 'replace all of them'. Anyone know any good online sites for cheap hoses? Cip1.ca is the only one I really use...

[KTPhil]

Running poorly will give a gas smell, not just richness. Unburned fuel smells rich but the reason for the unburned fuel may or may not be mixture. That is why the usual advice is to do a tuneup, to make sure other reasons are eliminated.

New hoses are a safety issue, not just for good running. 30psi can spew a lot of fuel on a hot motor!

When I put mine back on the road after years of sitting, it smelled rich, but it was actually too lean due to low fuel pressure. I turned it up from 24(!) to 30 and the smell disappeared.

Bad injector spray pattern (in my case due to low pressure) made a poor-burning mixture, so the fuel that didn't burn completely gave the exhaust a bad smell. So a lean mixture smelled rich!

Popping can also be from an exhaust leak admitting air into the hot exhaust along with the unburned fuel.

I'd really check everything else out before suspecting the EFI, other than it's hoses and wires (which account for 95% or more of "EFI problems.")

[Mike Fisher]

My new plastic fuel hose that "my people" bought at a home improvement store rather than rubber hose at a FLAPS is melted from being too close to the heat exchangers! My original "woven" hose had pin hole leaks! Going to Town now for some good old rubber fuel hose from a FLAPS! I can't believe that ordering fuel hose from the USA would be cheaper than buying at your Canadian FLAPS? Better replace them ALL regardless of cost!