Fixing a jimmy rigged electrical system

[gotyourgoat]

Yeah I think tha they are the original fuel lines. Thanks for the link. I'll have to look into that before long. Not sure how a return hose would work with two tanks if I eventually ge tthe second tank working too

Would work how it's supposed to from the factory. The other tank which you said was screwed shut likely has some sort of issue and/or it could have an issue with the tank switch. Did the seller have any info on this truck?

I get trying to do as little as possible to get going but doing it twice isn't any better on your wallet or your time. The return line helps with the vapor lock @SirRobyn0 was talking about. Aids in keeping a usable pressure while cooling of said fuel.

Honestly depending on the use of the truck and what it actually needs it might be worth a shot getting the proper pump and running new rubber lines back to the working tank. Attached to the frame of course. The old lines are in question of being physically there and their condition is a crap shoot. If the lines are indeed there and you hook them up causing 40 years of diesel and dirt to come out wrecking the new pump and the carb. That is no good and this thread will take a terrible turn.

 

[SirRobyn0]

I'll have to see. I'll probably focus on getting the truck running, but I assume that having a return hose might also help with gas mileage? I'm not actually sure what vapor lock is but it doesn't sound very good. The biggest thing for me is having a truck that will last for a while, but some of the work may need to happen in the summer when I don't need the plow and after a few paychecks

Vapor lock is when the gas gets hot enough boil and turn to vapor. Because the fuel pump produces pressure, and pressure increases the boiling temperature of fuel (in a similar way to water) vapor lock does not ussual happen after the pump. Typically the fuel boil in the line just before the fuel pump or in the pump, once that happens the engine runs very bad or stalls. The return line allows the pump to keep fuel moving in the lines at a high rate, which keeps the fuel cooler and prevents vapor locking. Vapor lock is typically a hot weather issue.

 

[jfrancom101]

Would work how it's supposed to from the factory. The other tank which you said was screwed shut likely has some sort of issue and/or it could have an issue with the tank switch. Did the seller have any info on this truck?

I get trying to do as little as possible to get going but doing it twice isn't any better on your wallet or your time. The return line helps with the vapor lock @SirRobyn0 was talking about. Aids in keeping a usable pressure while cooling of said fuel.

Honestly depending on the use of the truck and what it actually needs it might be worth a shot getting the proper pump and running new rubber lines back to the working tank. Attached to the frame of course. The old lines are in question of being physically there and their condition is a crap shoot. If the lines are indeed there and you hook them up causing 40 years of diesel and dirt to come out wrecking the new pump and the carb. That is no good and this thread will take a terrible turn.

Ok, yeah that does make sense. The seller didn't have much info on the truck. He only owned it for a couple of years. About how much $ and where would be a good place to get hose and a good pump? If I do go that route I'm guessing it would be a bit more expexnive and I'd proably need to wait a month or so and maybe stick with the electric for a little bit longer. Not sure

 

[Grit dog]

Did you get power to the distributor and get er running yet?
IMO, that's first priority.
RE the fuel pump, I only brought it up because I learned the hard way last year on my truck that with that little elect pump pulling fuel that distance, driving the truck further from home than I was comfortable walking back from was a mistake.
That said, I would 100% get a cheap mechanical pump and rig it up, even without sorting out everything else fuel related just to have a decent chance at a semi reliable fuel supply to the engine.

 

[jfrancom101]

Vapor lock is when the gas gets hot enough boil and turn to vapor. Because the fuel pump produces pressure, and pressure increases the boiling temperature of fuel (in a similar way to water) vapor lock does not ussual happen after the pump. Typically the fuel boil in the line just before the fuel pump or in the pump, once that happens the engine runs very bad or stalls. The return line allows the pump to keep fuel moving in the lines at a high rate, which keeps the fuel cooler and prevents vapor locking. Vapor lock is typically a hot weather issue.

Cool! Learning something new every day!

 

[jfrancom101]

I'm going to get the fusible link, but I can't find one that goes in the box like that anywhre. Is there a different name for it? And is there a standard amparage the is used?

 

[WP29P4A]

Yeah I ordered that as well. In the future is like to see if they have a battery run heat gun. For now I can use an extension cord but it would be nice for sure.

This is another option, I got a pair of these off Amazon for less than $20.00 Butane mini torch, Much easier to get into smaller spaces than a heat gun, but of course they require a bit of common sense to use safely.

 

[WP29P4A]

I'm going to get the fusible link, but I can't find one that goes in the box like that anywhre. Is there a different name for it? And is there a standard amparage the is used?

If you can't find the original type with two posts, you could use two of these side by side. One side can be the in the other side out, then just use the fusible link to bridge the two posts together.

 

[jfrancom101]

If you can't find the original type with two posts, you could use two of these side by side. One side can be the in the other side out, then just use the fusible link to bridge the two posts together.

(1973-91) Engine Wiring Junction Block

Plastic wiring junction block on firewall. With 2 studs. 73-87 pickup trucks and 88-91 Blazer, Suburban, & Crew Cab R/V series.

www.americanclassic.com

This one looks like it might be right. And for the fusible link itself?

https://www.napaonline.com/en/p/BK_7821344?cid=paidsearch_shopping_dcoe_google

Would something like this work?

 

[jfrancom101]

Did you get power to the distributor and get er running yet?
IMO, that's first priority.
RE the fuel pump, I only brought it up because I learned the hard way last year on my truck that with that little elect pump pulling fuel that distance, driving the truck further from home than I was comfortable walking back from was a mistake.
That said, I would 100% get a cheap mechanical pump and rig it up, even without sorting out everything else fuel related just to have a decent chance at a semi reliable fuel supply to the engine.

Still no power to the distributor. No power to the starter motor yet either. Still thinking about the fuel pump. I did a bit of sidework clearing snow and might have a paycheck coming sooner than I thought so I may want to do an OK pump sooner then later. Getting wiring figured out for the electric pump might be a waste of time if it's only used for a month

 

[WP29P4A]

(1973-91) Engine Wiring Junction Block

Plastic wiring junction block on firewall. With 2 studs. 73-87 pickup trucks and 88-91 Blazer, Suburban, & Crew Cab R/V series.

www.americanclassic.com

This one looks like it might be right. And for the fusible link itself?

https://www.napaonline.com/en/p/BK_7821344?cid=paidsearch_shopping_dcoe_google

Would something like this work?

The Junction block is perfect, I would use something like in the picture below, both available at Napa. The one on the left will make more than one fusible link, you just cut it to size and crimp on the ends that fit the studs you are attaching it to. And a little heat shrink to protect it.

When crimping on connectors, always pull on them to make sure the wire does not just pull out. You should be able to pull fairly firmly without the wire moving or pulling out of the connector. The wire going into the connector has to be large enough gauge to have something for the connector to grab when you crimp it down on the wire. Smashing the connector onto the wire is NOT the same as crimping it, crimp tool uses a pin to help secure the wire in the sleeve.

 

[WP29P4A]

Did you check the Ign fuse?

 

[AuroraGirl]

I agree with the thinking that a cheap pump $21 a cheap regulator $50 is $70 total. I have heard folks have good experiences with the carter pumps, but have no personal experience. I also agree with what Gotyourgoat is saying, the truck if it had come factory with a gas engine it would have had a return line, which would be beneficial in resisting vapor lock. I'm not sure how much Jeff wants to put into this truck or if making it like factory is something he is wanting. Another option is is he doesn't want to mess with a return line right off get one of the single in single out pumps, if he has issues with vapor locking there is a fuel filter he can install after the pump with built in return line port. I'd have to look up the PN for that. It's option, we use to install those on Dodge vans that had vapor lock issues, since they never came with a return line factory. We'd run rubber line for the return BTW, and it was always fine as long as it was secured well to the frame.

i think the design of the qjet can resist the pressure of fuel shoving at it better possibly because of the filter inlet maybe, but ive still heard of pressure overpowering

 

[AuroraGirl]

This is going to sound ghetto as hell but would a SBC with whats going on here work OK for diagnostics under gravity feed?Like to have it conitnuuous so he can check things, or is it gonna need to see a fuel pump of some kind?

 

[jfrancom101]

The Junction block is perfect, I would use something like in the picture below, both available at Napa. The one on the left will make more than one fusible link, you just cut it to size and crimp on the ends that fit the studs you are attaching it to. And a little heat shrink to protect it.

When crimping on connectors, always pull on them to make sure the wire does not just pull out. You should be able to pull fairly firmly without the wire moving or pulling out of the connector. The wire going into the connector has to be large enough gauge to have something for the connector to grab when you crimp it down on the wire. Smashing the connector onto the wire is NOT the same as crimping it, crimp tool uses a pin to help secure the wire in the sleeve.

How this is the crimping tool I've always used. I don't see a pin on mine. Do I need something different?
Also before I buy the part, does 14 gauge sound right to you?