Contaminated fuel or something else?

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jseabolt
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Contaminated fuel or something else?

Post by jseabolt » Tue Jul 09, 2019 10:18 am

I may have mentioned this awhile back. My Spider has developed a two part issue and I have no idea where to start looking.

I park my Subaru in spring and drive my other classics through the summer. I'll get one out and drive it for awhile, park it and drive another.

I drove my Spider back in March or April and got it out yesterday. Although it sat over the winter, I had driven it quite a bit so there should be fairly fresh fuel in it. Unless you don't consider three month old gas fresh.

It takes awhile for it to build up fuel pressure since it's bleeds off. Every now and then the car just stalls at idle just after starting it. But will restart with no problems. I maybe wrong but seems like once when it did this, the fuel gauge went to empty. This makes me wonder if it's something to do with the ignition switch failing. I'll have to see if I can catch this next time it does it.

Last year it did this after topping off the fuel tank as I was leaving the station. After it sat over the winter But the car was warmed up. But ran fine the rest of the summer. So it's not just doing this when cold. Well it stalled again the other day after it had been sitting since April or May. So I don't think engine temperature has anything to do with it.

Here's the main concern. This morning when driving to work it tended to hiccup a couple of times. Like a misfire. But in the engine does not stall.

A few years ago I had this bad misfire and gave the car a complete tuneup. I later traced the problem to the coolant temperature sensor. This thing had been leaking (the actual sensor not the copper gasket). The wires were corroded and one of the wires had broke so it was making an intermittent contact.

The first place to start (and easiest) would be the fuel itself. The car has 1/2 tank in it. The fuel recovery system is not functioning. So I'm wondering if in the three months it has sat there, water has condensed in the tank or the ethanol has absorbed it and it just picks up some of this stuff every now and then. Does that sound logical?

I'm not sure whether disconnect the line at the pump and drain the tank and start with new fuel or just put new fuel on top of what is already in the tank.

I've actually drained the tank a few times whenever I would have some weird issue crop up. But was never the cause. Always something else.

This problem could be anything. I always said if I have some issue with this 40 year old fuel injection system, I'm going to stick a Weber on it (but still keep my turbo and just blow through it like I am doing on my Yugo).

The other weird thing is my 2003 Subaru has been doing the same thing for 10 years! It also hicups around 3000 rpms at times but has never stalled. I've never been able to get to the bottom of that.

The Subaru usually bucks and carries on for a few miles after topping off the fuel tank.

All this makes me think something like water is getting agitated inside the tank or a mixture of alcohol and water due to moisture getting in the tank from a hose venting to the atmosphere.

Also keep in mind 100% gas can still get contaminated with water. I run 100% gas in my lawnmowers and have still had issues where water condensed in the fuel tank over the winter and blinded the fuel filter over with water so gas would not pass through it. So there is some sense of false security that running 100% gas won't get contaminated with the water. Water just won't mix with gas. It just mixes with the alcohol and sinks to the bottom just like water would do.
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Re: Contaminated fuel or something else?

Post by 18Fiatsandcounting » Tue Jul 09, 2019 12:04 pm

There's a lot in your description to chew on, especially given that this could be either an electrical problem or a fuel issue, and the first big step would be to narrow down which it is. Given your observation about the fuel gauge, it sounds electrical, but there could be more than one thing going on. With the engine running, try gently moving the bundle of wires at the back of the ignition switch back and forth, up and down. If the engine cuts out when you do that, then yes, bad ignition switch or a loose connection.

Do you buy your gas at the same place each time? Some stations are pretty weak when it comes to keeping water out of their storage tanks, so you could try another gas station. Unless your gas tank and/or lines have a major opening to the outside, it's hard to imagine getting enough water in there in a few months to be a problem, but then again, if your car experiences wide temperature fluctuations in a humid environment, I suppose it's possible.

-Bryan
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rridge
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Re: Contaminated fuel or something else?

Post by rridge » Tue Jul 09, 2019 12:35 pm

It's pretty easy to rule out contaminated fuel. Disconnect the fuel line at the pump, drain the tank, and pull the sender to check the condition of the tank. Shake any water or debris out of the pump and put a new fuel filter in while you are at it.

Checking for something else takes a bit longer. I once had a mis-machined distributor cap that produced the same hiccups while cruising along at a steady pace. Always makes sense to rule out easy ignition stuff before getting too far into the FI side.

The FI system has its own fuse and power supply but the double relay needs a signal from the ignition switch to switch on the power to the FI harness, so the double relay and that signal line are the link between the ignition switch and the FI harness. I found a failed contact in the double relay connector that provided that link just a couple weeks ago. See my recent post and a picture. The easiest way I know to rule out the double relay itself is to get out your spare double relay, the one you keep in the glove box at all times.

If the problem is a flaky ignition switch the hiccup could be coming from loss of voltage at the coil. Brief instantaneous interruptions are usually on the ignition and electrical side.
Richard
'81 Turbo Spider
Rockville, MD
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Re: Contaminated fuel or something else?

Post by jseabolt » Tue Jul 09, 2019 5:31 pm

18Fiatsandcounting wrote:
Tue Jul 09, 2019 12:04 pm
There's a lot in your description to chew on, especially given that this could be either an electrical problem or a fuel issue, and the first big step would be to narrow down which it is. Given your observation about the fuel gauge, it sounds electrical, but there could be more than one thing going on. With the engine running, try gently moving the bundle of wires at the back of the ignition switch back and forth, up and down. If the engine cuts out when you do that, then yes, bad ignition switch or a loose connection.

Do you buy your gas at the same place each time? Some stations are pretty weak when it comes to keeping water out of their storage tanks, so you could try another gas station. Unless your gas tank and/or lines have a major opening to the outside, it's hard to imagine getting enough water in there in a few months to be a problem, but then again, if your car experiences wide temperature fluctuations in a humid environment, I suppose it's possible.

-Bryan
I grabbed the harness at the back of the ignition switch when I got to work and shook it to see if this had any effect. It didn't. But next time this happens I will try to look at the gauges to see if they go dead.

I can't remember where I got this last tank of gas from. This stalling at idle happened spring of last year just after topping off the tank. The gas that was in it was from the previous fall. If I remember, it seems the engine didn't run as smooth until I topped the tank off. The engine didn't ping. But seemed like it ran better after topping off the fuel tank with fresh gas.

I have been using that Sta-Bil ethanol treatment in the fall before putting my cars up for the winter. I really don't know if it does anything like preventing phase separation.

It seems like there is something cutting out for it to cause the engine to stall at idle. I believe this hiccup I felt twice coming to work is somehow related. When this happened I just got through crossing a bridge that makes a sharp S. That's why I wondered if the fuel in the tank sloshing around caused the pump to pick up any junk like water. I had already driven about 6 miles so I'd think by that time, anything in the tank would have been stirred up.

I think I'm going to drain the tank and start with some fresh fuel before I start replacing stuff.
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Re: Contaminated fuel or something else?

Post by jseabolt » Tue Jul 09, 2019 5:41 pm

rridge wrote:
Tue Jul 09, 2019 12:35 pm
It's pretty easy to rule out contaminated fuel. Disconnect the fuel line at the pump, drain the tank, and pull the sender to check the condition of the tank. Shake any water or debris out of the pump and put a new fuel filter in while you are at it.

Checking for something else takes a bit longer. I once had a mis-machined distributor cap that produced the same hiccups while cruising along at a steady pace. Always makes sense to rule out easy ignition stuff before getting too far into the FI side.

The FI system has its own fuse and power supply but the double relay needs a signal from the ignition switch to switch on the power to the FI harness, so the double relay and that signal line are the link between the ignition switch and the FI harness. I found a failed contact in the double relay connector that provided that link just a couple weeks ago. See my recent post and a picture. The easiest way I know to rule out the double relay itself is to get out your spare double relay, the one you keep in the glove box at all times.

If the problem is a flaky ignition switch the hiccup could be coming from loss of voltage at the coil. Brief instantaneous interruptions are usually on the ignition and electrical side.

That coolant temperature sensor really stumped me a couple of years ago. I thought it was ignition related. How I discovered it was whenever the hood was down, the engine misfired but with the hood up it idled fine. I'll give that another look.

I actually keep a spare double relay in the trunk. I've never had to use it.

These fuel injection systems are getting close to 40 years old. They can't last forever. It could be anything like a bad solder in the computer for example. And as expensive as Bosch components are, it would probably be easier and cheaper to stick a Weber on it and be done with it than try to figure the problem out if it comes to that.

Years ago I knew a guy who owned a Nissan Stanza. This car would just die for no apparent reason every couple of weeks or so. He said he would have to let the car sit for about 30 minutes before it would restart. Like something was getting hot.

He had the dealership look at it. They could not find anything wrong with. They told him he was going to have to wait until whatever was wrong burned out and the car refused to start. A mechanic did give him a tip. He said whenever his happened to unplug the computer for 30 seconds. He said this worked. Eventually he got tired of disconnecting the computer and traded it in.
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Re: Contaminated fuel or something else?

Post by jseabolt » Wed Jul 10, 2019 6:31 am

I drove the car home (8 miles) and today again (8 miles) and it never missed a beat. So as of now, I'm not going to worry about it. Like I said my Subaru does this same thing every now and then so I guess when you got all that electrical signals going on, expect a fluke to happen at some point. Not saying it's related to the fuel injection system but nothing beats a good old Weber in my opinion!

I still think it's some crap in the fuel. There is a new gas station on the way to work I'm going to start getting my fuel from. The other two stations in my area are starting to get kind of ghetto looking so who knows the condition if their tanks.
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Re: Contaminated fuel or something else?

Post by bartigue » Wed Jul 10, 2019 7:22 am

Sounds a lot like how my 82 was behaving when I first got it. Rust in the tank, rust in the pump, rust in the filter. The pressure would occasionally get so low it would die, then it would run fine for a while. Easy enough to diagnose by simply dropping the hose between the pump and filter and seeing if gas or gas+contaminates spill out.
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Re: Contaminated fuel or something else?

Post by rridge » Wed Jul 10, 2019 7:45 am

The weak points of the FI system are the double relay, the temp sensor, and the connectors. You can still find OEM quality replacement parts for three because they were used in many other cars. If you use low grade replacement parts and neglect rubber hose renewal frustrations will result. The biggest challenge for an FI system is not a weak solder joint in the ECU but a rusty fuel tank. And that is equally true of a carb based fuel system.
Richard
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Re: Contaminated fuel or something else?

Post by daver80 » Thu Jul 11, 2019 10:56 pm

My 2 cents lol... it sounds like you're painting the same picture I "was" having the last couple of months.
I've always filled the tank and put it away around Oct/Nov weather permitting. Start it up in April? and go from there. Well for the first time in 20 years, I had starting problems. changed plugs, no good. Well for chits and giggles I had some gasline antifreeze, put in a little container and 20 minutes later it fired right up. Had about 3/4 tank so put in 2ish gallons of high test and I guess I am off to the races for another summer.
It started every time I tried it, the past 3 weeks.

good luck with your ride, hope its just the gas also, whew might have dodged one there lol

Dave
1980 fiat spider
fuel injection
It goes 0 to winery in just over 4 taster tests
and it's red, go figure
wait no, it's cherry rossa
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Re: Contaminated fuel or something else?

Post by jseabolt » Fri Jul 12, 2019 8:57 am

It's got to be the fuel.

When the car sits for an extended period of time wheather it be two or six months this tends to happen.

After this incident Monday, the car has ran fine the rest of the week and hasn't even stalled at idle. Another weird thing. The idle speed has also increased a little bit. Like maybe 100 rpms.

It's at 1/4 tank now. I think I will just run it down until the light kicks in and top it off.
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