22RTE-Trucks
March 22, 2019, 10:24:48 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News:

Hi all - Welcome back for the second time this month!

I apologize for the inconvenience of the site being offline. The site was down for technical reasons, but it didn't help that I was of offline for two weeks (camping and travel). Once I got back, it took a while to get things sorted out. That's resolved, and the site is now back up. Huzzah!

Please take a minute and read the Site News thread I've posted in the General section, and feel free to comment. Thanks!

mosk
Admin



 
   Home   Help Search Login Register  
Pages: [1]
  Print  
Author Topic: 1987 backfiring...electrical or fuel?  (Read 2887 times)
tra8cer2
Newbie
*
Posts: 5



View Profile
« on: October 26, 2015, 09:05:52 PM »

Hello,

I am new to this forum and need some help.

Just bought a 87 4 runner that came with a misfire after sitting for the past 7-9 years.  The previous owner installed a reman engine and put about 10k on it before parking it.  He also purchased the larger turbo kit from Turbo Engineering and that has only 500 miles on it before it was parked.  This is the fourth 4runner I have owned and I plan on having this truck for a long time!  That being said, I have a few questions:

Here are the problems I want to spitball with you guys:

Hard to start only when cold- I'm assuming a weak fuel pump...so which one should I go with?
runs rough at idle and no power until after 2,500 rpm and then it backfires like crazy- not too sure on this but I'm assuming after doing the fuel pump I plan on replacing the tank, fuel lines, injectors etc.

What I have replaced and done so far:

Replaced spark plugs, wires, distributor, and rotor
replaced fuel filter and it was nasty!
I verified the timing was proper.
Previous owner checked the function of the valves and they all work properly.

I don't have much experience on troubleshooting electrical and I don't have the tools to run a compression check on the motor to make sure I don't have a dead cylinder so any help would be appreciated!  I have the motor down to the injectors so I can test them, I'm just not sure what the readings should be for the wires going into the injectors or the injectors themselves.

Also anyone know of someone willing to "build" a stock harness?  or is there a universal kit that has the correct size and type of wires for me to lay this thing out and do it myself?  I'm really not wanting to do it, but I don't trust buying used harnesses only due to the age and the fact that the insulation is coming apart on mine and want to remove the possibility of this being an electrical chasing nightmare!

I am also on the lookout for the actual book or electronic version of the service manual for my truck.  Any vehicle I buy I prefer having the manual on paper and realized I must have gotten rid of my chiltons manual I had before.

Thanks for the help in advance!

Logged
psychohamster
Two cylinders
***
Posts: 190


View Profile
« Reply #1 on: October 27, 2015, 01:06:19 AM »

Check your codes (like Ronmar told me to do).
If your showing an 11 your problem is probably your TPS.
With it warm and at idle jump TE1 and E1 and if it doesn't immediately idle down then I would say it's your TPS and you won't be able to time it right before that is working correctly.

I put a new TPS unit on mine (cost me $80). I took off the Throttle Body and douched it out with brake cleaner, adjusted the butterfly/throttle plate to specs, adjusted the dashpot and put on the new TPS and dialed it in with a multi-meter and feeler gauges as per the manual (swap out the Phillips screws for Allen heads).

My truck then ran perfect (until I broke something else totally unrelated). I was throwing 4 codes and once I did the TPS it coded Normal (1 flash).

This is what worked for me, hopefully it might give you something to look at and either address or scratch off the check list.

Good luck

Also check the function of your MAF.
« Last Edit: October 27, 2015, 01:09:13 AM by psychohamster » Logged
tra8cer2
Newbie
*
Posts: 5



View Profile
« Reply #2 on: October 28, 2015, 02:14:45 PM »

It has been a while since I have checked codes on a older vehicle...How do I do this on the 4runner?

I am actually looking to just buy a new TPS and MAF because honestly I'm needing this to be running before the snow starts to fly.

Any other tips I need to know before I get these parts and start putting them in?
Logged
psychohamster
Two cylinders
***
Posts: 190


View Profile
« Reply #3 on: October 28, 2015, 05:24:20 PM »

Save your money and check the codes.
I sure could have if I did that first.

Get a repair manual and it will give you alot of info as to how and what, but off hand an 87 has a different unit to use a jump wire on then my 86.

It involves using a short wire and shorting out TE1 and E1 in the wiring and reading the number of flash sequences at the check engine light. You need to take care and read them correctly so alittle research could save you a bunch of money and frustration.

Do a "search" on this site for "codes" and you should get an idea of how to do it right.
I wish I had when I started working on mine.

Good Luck
Logged
tra8cer2
Newbie
*
Posts: 5



View Profile
« Reply #4 on: December 08, 2015, 01:27:42 AM »

So I pulled apart to the fuel injectors and found two out of four of them were pretty much blocked with rust.

What I have done since then:

Replaced the injectors
Replaced the crappy wire connectors for the injectors with fresh ones
replaced the fuel pump
replaced the fuel tank
Blew out the fuel lines
replaced the vacuum lines with silicone lines (gotta look nice under the hood too!)
replaced the MAF

The good....  It runs a crapton better!
the bad....... Only runs if I feather the gas...if i let off the rpms drop down to 200-300 and then dies
Can anyone direct me to how to ensure the idle remains around 800-900?  I am not familiar with turbo and I see two places to adjust the idle as well as what the correct timing should be?  It has 10,000 miles on a reman engine and 500 miles on I believe a turbo from turbo engineering corp...
I have upgraded the fuel pump to a  HFP 255LPH Fuel Pump and the injectors are oem so I understand that increases the fuel input.

I also know I need a new battery....left the doors open too much...

Any help would be appreciated!

I am currently waiting on an actual service manual at this time as well!
Logged
psychohamster
Two cylinders
***
Posts: 190


View Profile
« Reply #5 on: December 08, 2015, 04:42:52 AM »

I recently found out the hard and pricey way that it wasn't a fuel issue for my truck , it was a fuel management issue.
I strongly recommend you remove and clean your throttle body and check your Throttle Position Sensor that is located on the TB. Adjust it as outlined at http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml It won't cost you anything more then some time and some carb cleaner. Also, as I learned from Ronmar, check your codes. I didn't at first and it cost me alot of time and money.

I was driving my sons 86 22rte 2wd as I was fixing mine and his truck is new from the waterpump to the rearend with a new LCE turbo kit, but I found his TPS was bad. I replaced it (adjusting it is critical for top performance) and the bottomend improved dramatically. It also surged to the point it would die from brake boost vacuum and that is all but gone.
Additionally, if your TPS is messed up you won't be able to time it correctly.
Douche the Throttle Body and check your TPS. Make sure all the passages are clear too.
Logged
CMG
Two cylinders
***
Posts: 275


View Profile
« Reply #6 on: January 27, 2017, 03:21:15 AM »

Another possibility that comes to mind when backfiring occurs is the AFM.  The little flap door is connected to a potentiometer that can be worn down in places or dirty, and sometimes it is clocked (adjusted) as an old school tuning method.  At the least you can visually check the top box on the AFM and se if it has silicone or holes or anything that does not look stock and looks like someone opened it. 
Logged
Pages: [1]
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!