slight dead spot in throttle range .. what to check ?

[i need help & guidance]

i changed accelerator pump and looked at ficd and other vacuum lines and stuff.

 

but just wondering if a nissan shop manual that anyone has  . .  might just say what to adjust . if there is a acceleration dead spot

 

while taking off from a stop

 

  i already checked all vacuum lines and stuff.

 

i just need help with which adjustment screw to set.

 

  i am also going to try moving lock nut on throttle cable to see if i get any change

Edited December 11, 2018 by i need help & guidance

[datzenmike]

Acceleration dead spot? Like the truck just stops going any faster?

 

 

Better just say what it does when you drive it.

[i need help & guidance]

also. is it possible ? .  the vacuum advance can quit working

 

even though distributor part  still works ?

[datzenmike]

Take the distributor cap off and suck on the hose going to the vacuum advance canister. What you should see is the rotor rotate clockwise about an inch and hold till you release the suction. If it does this then it's physically working.

[i need help & guidance]

ok, . i will try and post findings . .  thank you

[i need help & guidance]

any idea what factory oem part number is for just the vacuum advance - part ?

 

  or the nissan oem # factory part number for the distributor ? 

[datzenmike]

13 hours ago, datzenmike said:

Take the distributor cap off and suck on the hose going to the vacuum advance canister. What you should see is the rotor rotate clockwise about an inch and hold till you release the suction. If it does this then it's physically working.

 

 

Did you do this? It's either working or not working.

 

 

15 hours ago, datzenmike said:

Acceleration dead spot? Like the truck just stops going any faster?

 

 

Better just say what it does when you drive it.

 

What about this? What does it do when driving??? Explain.

.

 

 

[i need help & guidance]

there is a acceleration dead spot , while taking off from any  stop

 

 the engine runs fine and idles fine. but when taking off from stop sign OR traffic light or what ever. just when you begin to press gas pedal

 

the engine cuts out just enough to stall engine. some times

 

so i have to stomp gas more than i want , to take off

and this puts stress on drive shaft center bearing which needs replaced because i can hear driveline bang around for moment when i stomp on the gas

 

so i went to troubleshooting page of haynes manual and it says

 

........first check these 5 things

 

 1. ignition timing is incorrect . i checked timing it was slightly advanced. so i put it back to stock point as it says under hood on badge . and the hesitation got worse .

so i put it back where it was .

i did not try advancing it further cause it got dark and cold after sun went down .

 

2. check ignition see if not operating properly .  i not see anything obvious here . but it was getting dark

 

3.  dirty or clocgged carb or fuel injectors..  before i put on new gas tank and filters and fuel pump we ran sea foam through and blew out the lines all the way to carb ,,, with the air hose , and used carb and choke clean spray and brushes and rag to clean out carb

 

4. low fuel pressure  .  it says check for clogged fuel lines and make sure you have correct fuel pressure ......................  i think i do ,

............. since now the truck is fast enough to  go out on fwy  with passing power it never had before .

 

5.  carb out of adjustment .  it passed smog and fuel sight bowl level seems correct as stated in haynes manual

 

..................

 

what i did find yesterday was ... a vacuum hose had came off the magnet switch-  f.i.c.d.  thing on fire wall.

so i put new hose on it..  but it says this thing only works when i turn on the a/c .

..... i did blow air through the  magnet switch new hose - that goes to carb, and i can see the hammer thing it operates at back of carb , move

 

so i thought if i knew the actual part number for distributor and vacuum advance pieces.

 

i can acquire the new parts vs buying RE-manufactured re-part numbered items .

 

i skimmed  through haynes manual but not sure where to look to locate actual OEM part numbers of each item i need

Edited December 12, 2018 by i need help & guidance

[i need help & guidance]

 i took distributor part

 

and red magnet that is under stator thing

red magnet is under the goal post type thing the reluctor spins past and requires the .3mm air gap

 .... is cracked .

 

i cant find this magnet's part name or part number for it

Edited December 12, 2018 by i need help & guidance

[DanielC]

If your truck has a carburetor, check the accelerator pump.  This is a plunger on the side of the carb, operated by lever, attached to the throttle shaft, or linkage.

With the air cleaner off, and engine not running, look down the primary (smaller) carb throat.  when the gas pedal is pushed, you should see a small squirt. or jet of gasoline douw toward the throttle plate.

[i need help & guidance]

i replaced that already .. see my other thread  . .  .

 

....  i am at this phase of repair now

[i need help & guidance]

the part is called

Distributor Ignition Pickup magnet  .

it is labeled as part number 22158

... on shop parts break down paper

 

it goes under neath part number 22163

Edited December 12, 2018 by i need help & guidance

[datzenmike]

Before you go and spend money on something that may not even be related do some detective work.

 

 

Ignition...

Are both intake and the exhaust side plugs firing? Pull a plug off each side and stick an old plug in the end and lay on a grounded surface like the manifold. Crank the engine with the starter.... got spark???

 

Are your ignition wires in good shape and clean? Are they or the nipples cracked, dries out or broken?

 

Are the spark plugs clean on the outside? or all covered with dirt and oil? Clean the porcelain insulator or replace them if worn out.

 

Pull the cap and unscrew the rotor and have a good look at them. If old and worn replace them. Look for carbon tracking which is where the insulation has broken down and the spark finds a path to ground other than the spark plug. It will look like a crack but it's a burned path the spark makes. It can be on the inside or outside of the cap or anywhere on the rotor. Carbon tracking can also be across the porcelain insulator on the spark plugs. Or the insulator may be cracked. 

 

Remove the center wire on the coils and carefully inspect the insulation for carbon tracking near the negative terminal or even a crack in the plastic.

 

 

Just remember that spark always always always searches for the easiest path to ground. What you have to do is make the spark plug the easiest path by having good insulation. Cap rotor, wires, coils and plugs. 

 

 

 

 

Here's my coil from over a year ago. I drove with this for about 6 years and always wondered why it hesitated just as the car started to move forward as I let the clutch out. I tried everything and gave up. (and often stall, embarrassing when pulling out on the highway with cars coming) Last winter I drove in the cold and the car backfired out the exhaust which can only happen if there is an interruption of ignition spark and unburned gas gets past and into the exhaust pipe.

 

So I had a good look and the coil was carbon tracked right by the negative terminal under the nipple out of sight. Spark would briefly arc along this path rather than go to the plugs. When the spark finally got through it would explode the gas in the exhaust. Threw a spare coil on and it never did it again.

 

Not saying this is the cause just that it could be and should be eliminated first before you spend money on new parts that won't fit it.

[datzenmike]

Fuel...

 

5 hours ago, DanielC said:

If your truck has a carburetor, check the accelerator pump.  This is a plunger on the side of the carb, operated by lever, attached to the throttle shaft, or linkage.

With the air cleaner off, and engine not running, look down the primary (smaller) carb throat.  when the gas pedal is pushed, you should see a small squirt. or jet of gasoline douw toward the throttle plate.

 

Check visually that you are indeed getting a good strong squirt of raw fuel just as the throttle is opened.  If weak or sometimes a dead spot this will need fixing.

 

There are two BB in the pump system. Both act as one way valves. One allows fuel in from the float chamber but prevents the pump from pushing it back. The other is on the outlet, letting fuel out on the down swing but closing on the up swing to prevent air being sucked back in.

 

There are some adjustments on the accelerator arm to increase the squirt volume.

 

The accelerator pump supplies additional fuel to transition between the idle circuit and the primary barrel use. The engine isn't turning fast enough just above idle to form a strong enough vacuum to draw fuel in and goes severely lean.

.

[i need help & guidance]

 . . .  each thing i fix.

.........causes another thing to break. ......  i still working on this . . .

[datzenmike]

Often removing a problem allows the one behind it to show.