FRUSTRATION! worked on heater fan and now truck won't start

[jwilson645]

This is a really weird thing and I'm fairly certain that the 2 things are not related because before I started working on it, I had it started up and running to warm up so I could test the heat. I didn't touch anything other than swap out the heater fan and put a jumper on the fan relay to find out it was bad. Now it only turns over but will not start. If I spray some carb cleaner in the carb it will almost run or run for a second but then backfire through the carb and die. This tells me it has spark.

Looking in the carb, i'm only getting spray on one side of the primaries. I just did a full rebuild on this Qjet a year ago, using all parts from Cliff's High Performance and made the changes that were suggested from him. It's been running perfect, aside from being a tad rich. I have a Summit fuel pressure regulator on it set at 5psi and a Napa mechanical fuel pump.

I think the whole thing is fuel related but the backfire has me confused. I haven't touched the timing or anything. Could a fuel issue cause the pop through the carb or was that likely because of me spraying the carb cleaner in there?

Engine was fully rebuilt by me with help here and has been running great until this.

[kwmech]

Somewhere along the line you knocked a wire loose going to the distributor. Check voltage to the coil

[Dead Parrot]

2nd on the magic elbows knocking something loose. Make sure the distributor is tight. If it worked loose since your rebuild, your being under the hood installing things and moving stuff around might have changed your timing.

[homemade87]

The pop from the carb was most likely from a lean condition ( no fuel ) . What I would do is pour some gas in the carb and see if you get a longer run time before it burns that fuel up . It may take a little cranking for it to start at first . If it does you have lost your fuel source . This will eliminate dist problems .

This is a shot in the dark , but are you working on the truck outside . Right now where you are it has not been above 25 and lows in the single digit at night for the past couple of days . Maybe moisture in the fuel line .

You should have two healthy fuel shots from the carb squirters on the carb . If not then you definitely have a fuel problem .

My guess is fuel related .

[jwilson645]

Originally Posted by homemade87

The pop from the carb was most likely from a lean condition ( no fuel ) . What I would do is pour some gas in the carb and see if you get a longer run time before it burns that fuel up . It may take a little cranking for it to start at first . If it does you have lost your fuel source . This will eliminate dist problems .

This is a shot in the dark , but are you working on the truck outside . Right now where you are it has not been above 25 and lows in the single digit at night for the past couple of days . Maybe moisture in the fuel line .

You should have two healthy fuel shots from the carb squirters on the carb . If not then you definitely have a fuel problem .

My guess is fuel related .

I'm pretty sure you are right. I honestly don't think it is an ignition problem because I had it run for a few seconds by spraying the carb cleaner in there. Yes, I'm working on it outside but haven't touched it since last Saturday when it was in the 50's.

I have an inline clear filter so I was able to see the fuel but the last attempt at cranking, the fuel was not filling that filter just shooting up into it. I'm wondering if there isn't something wrong with the mechanical fuel pump or maybe my first filter is clogged (there are 2 inline).

[jwilson645]

Originally Posted by kwmech

Somewhere along the line you knocked a wire loose going to the distributor. Check voltage to the coil

Originally Posted by Dead Parrot

2nd on the magic elbows knocking something loose. Make sure the distributor is tight. If it worked loose since your rebuild, your being under the hood installing things and moving stuff around might have changed your timing.

I have checked power going to the distributor and it's good. Also checked to make sure it was tight and it was all good.

[v30crewcab]

out of fuel, or timing chain jumped?

[wilkin250r]

Starting fluid is a great diagnostic tool. If it runs for a second on starting fluid, it usually tells you that your engine is good, that your spark and timing is acceptable, and the engine itself is ready to run.

Basically, if it starts and runs a second on starting fluid, it tells you that you have a fuel delivery problem.

If you ever find a situation where it DOESN'T start with starting fluid, that tells you that you have an engine or ignition problem.

[andyh1956]

Try filling the carb bowl up with fuel from the vent & see if it will pump from acc pump nozzles then & start.

[jwilson645]

Just thought I'd give an update to this. It's been a while in the works but I hurt my back and haven't worked on the truck in a while.

Turns out that the problem was caused by an old, deteriorated in tank filter. The carb was only shooting out of one side because trash had gotten in it. After a total disassemble and cleaning it was working but still not pulling fuel up from the tank, i put a long hose on the pump and inserted it in a gas can it pulled just fine. This told me there was a blockage somewhere else and I figured that filter had never been changed (knew it hadn't since I've had the truck) so I dropped the tank and replaced that sock filter, all the rubber line from the tank to the steel fuel line, bypassed the dual tank valve (had already been rigged to only pull from one tank but was still going through the valve) and blew compressed air through the metal line to make sure there was not blockages there. Once I hooked the fuel line back up she fired right up.

[Max1775]

Awesome! Gotta love it when you do something simple and then something completely unrelated causes issues. Makes you think you're going nuts... 🤪

[jwilson645]

Originally Posted by Max1775

Awesome! Gotta love it when you do something simple and then something completely unrelated causes issues. Makes you think you're going nuts... 🤪

You got that right. Was such a weird thing. Sometimes you just have to step back and troubleshoot instead of throwing parts at what you THINK is the problem.