How can I accurately check my fuel system/ injectors/ pressure/ fuses.

try injector & fuel system cleaner, check throttle body & injectors for cleanliness, also run diagnostic on sensors, check vaccuum lines for pin holes, does it do it if you foorboard the gas ped. when it hesitates ?

was the engine getting fuel or was their no spark ----need to establish if fuel or ignition problem ---running out of fuel may have damaged pump -deadspot -overheat ---problem with relay need to check and test the system ---

This sounds like a fuel pump or fuel filter problem.
The 1988 Jetta has two fuel pumps. The "main" one under the car directly in front of the gas tank on the right hand side. The other fuel pum is in the tank. You can access that fuel pum by removing the round access panel in the trunk towards the back seat.

You'll need a fuel pressure gauge. You can usually borrow one from a large auto parts chain store.

FUEL DELIVERY & SYSTEM PRESSURES
System Pressure
Connect Pressure Gauge (VW 1318) between line from fuel distributor to cold start valve and
test port connection on lower chamber of fuel distributor, using Adapter Fittings (VW 1318/5).
Test port is sealed by a threaded plug. Bridge fuel pump relay with Jumper Switch (US 4480/3).
1.
Disconnect wiring from Differential Pressure Regulator (DPR). Open valve on pressure gauge
(points at cold start valve line when open) and activate fuel pump. System pressure must be 75-
82 psi (5.3-5.8 kg/cm2 ). If pressure reading is low and fuel pump delivery quantity is good,
replace pressure regulator.
2.
If pressure reading is high, disconnect fuel tank return line from DPR. Repeat test. If reading is
correct, check for plugged return line. If reading is incorrect with line open, replace DPR.
3.
Differential Control Pressure
Close valve on pressure gauge. Activate fuel pump with jumper switch. Leave DPR
disconnected. DPR reading should be 2.9-7.0 psi (.2-.5 kg/cm2 ) less than system pressure. If
pressure is incorrect, disconnect lower chamber return line and measure volume.
1.
Close open port to diaphragm pressure regulator. Activate fuel pump with jumper switch. Fuel
volume should be .14-.16 qts. (.13-.15L) for period of one minute. If volume is correct, replace
DPR. If volume is incorrect, replace fuel distributor.
2.
Close valve on pressure gauge. Install Test Harness (1315A/1) between DPR and vehicle
harness. Set multimeter to DCA 200 mA scale. Connect multimeter to test harness. Disconnect
wiring to coolant temperature sensor. Connect 15 k/ohm side of Test Resistor (VW 1490) to
sensor wiring.
3.
Turn on ignition and fuel pump. Differential pressure should be 10-17.5 psi (.7-1.2 kg/cm2 )
less than system pressure. DPR current should be 50-80 mA. If pressure is incorrect and current
is correct, replace DPR.
4.
If both pressure and current readings are incorrect, remove test harness from DPR. Ensure
resistance of DPR is 17.5-21.5 ohms. If reading is incorrect, replace DPR.
5.
If reading is correct, check ground from temperature sensor to cold start valve. If ground is
good, check power supply fuse. If fuse is okay, check terminals on ECU connector. If connector
is okay, replace ECU.
6.
Residual Pressure & Internal Leak Testing
Open valve on pressure gauge. Operate fuel pump for 30 seconds. Pressure can drop to a
minimum of 38 psi (2.7 kg/cm2 ) after 10 minutes. If pressure drops below specification, inspect
fuel pump check valve and all fuel fittings for leakage.
1.
NOTE: Pressure and leak testing does not include checking cold start
valve.
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If there are no leaks, check airflow sensor plate clearance. If plate clearance is correct, replace
diaphragm pressure regulator and repeat leak test. If pressure drop is not within specification,
replace fuel distributor "O" rings.
2.
Transfer Pump Delivery Volume
Check voltage supply to pumps. Connect Jumper Switch (US 4480/3) in place of fuel pump
relay, on relay panel. Remove fuel filler cap. Disconnect and plug off Black fuel line from
sending unit.
1.
Connect hose to sender port and place in measuring container. Turn on fuel pumps. Minimum
transfer pump delivery volume should be .42 qts. (.4L) in 10 seconds. Reconnect fuel line to
sender.
2.
Main Pump Delivery Volume
Check transfer pump (if equipped) and fuel filter. Disconnect fuel return line and place in
measuring container. Switch on fuel pump with jumper switch. Check fuel pump delivery
volume for 30 second period. Delivery rates are given with voltage reading at pump as volume
will change with different voltages.
1.
Minimum delivery volume for Fox, Quantum and Quantum Syncro models is .71 qts. (.68L) for
30 seconds with reading of 11.4 volts at fuel pump. Minimum delivery volume for other models
is .62 qts. (.59L) with 11.4 volts at fuel pump.
2.
Fuel Distributor
Check sensor plate adjusting lever and fuel distributor control piston for smooth operation.
Disconnect fuel injector lines at fuel injectors.
1.
Remove fuel pump relay and bridge fuel pump circuit. Use Jumper Switch (US 4480/3) in place
of fuel pump relay. When pressure has built up, turn off fuel pump. Move sensor plate from rest
position to end of travel.
2.
Uniform resistance should be felt during entire movement. No resistance should be felt on
quick return to rest position. Connect injector lines. Install fuel pump relay.
3.
Injector Quantity Comparison
Remove fuel pump relay, from relay panel, and install Jumper Switch (US 4480/3) in off
position in place of relay. Attach Fuel Quantity Analyzer (US 4480) to bumper and secure in
place. Remove injectors from cylinder head with fuel lines attached. Check and replace fuel
injector "O" rings as necessary.
1.
Check tightness of injector insert (2-piece inserts). If inserts are loose, remove and clean
threads. Use sealing compound when installing upper insert. Replace sealing washer that goes
against cylinder head below lower portion of insert. Lubricate injector "O" rings with gasoline
and install injectors, with fuel lines connected, into fuel quantity analyzer tubes.
2.
Ensure lines are not kinked or bent. Loosen fittings to align fuel lines and retighten. Remove
rubber boot from airflow sensor housing above sensor plate. Turn and lift setting screw and
adjusting slide of Sensor Plate Adjustable Holder (VW 1348/1) into upper position. This
simulates full throttle operation. See Fig. 11 .
3.
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Fig. 11: Sensor Plate Adjustable Holder (VW 1348/1)
Courtesy of AUDI OF AMERICA, INC.
Place sensor plate adjustable holder on airflow sensor housing with holder centered over plate.
Pointer on edge of holder base must point toward center of fuel distributor. Push adjusting slide
of holder down onto stop.
4.
Turn adjusting screw clockwise until magnetic end touches sensor plate retaining bolt. Activate
fuel pump with jumper switch. Turn adjusting screw of holder counterclockwise until any one
injector starts to deliver fuel. Turn off jumper switch and empty fuel quantity analyzer after
taking sample.
5.
Idle injection quantity is measured first. Lifting adjusting slide of holder to first stop simulates
idle position of sensor plate. Activate fuel pump until fuel level reaches 20 ml on scale of any
tube.
6.
Check that all injectors have identical spray patterns that are even and cone-shaped. If not, raise
sensor plate up quickly to full lift position and release. Repeat idle quantity test. Compare
amounts of fuel delivered by all injectors with analyzer held level. Maximum difference in
delivery quantity between injectors is 3.0 ml of fuel.
7.
If fuel delivery quantity differs between high and low levels by more than 3.0 ml, interchange
injectors and repeat test. If difference of delivery quantity changes with injectors, replace
injectors. If difference of delivery quantity does not change with movement of injectors, either
fuel lines are pinched or fuel distributor is defective.
8.
Measure full throttle injection quantity. Empty analyzer into fuel tank and reinstall injectors in
analyzer. Lift adjusting slide of holder to last stop to simulate full throttle position of sensor
plate. Activate fuel pump with jumper switch until fuel level reaches 80 ml on scale of any tube
of analyzer.
9.
Check that all injectors have identical spray patterns that are even and cone-shaped. If not, raise
sensor plate up quickly to full lift position and release. Repeat full throttle quantity test.
Compare amounts of fuel delivered by all injectors with analyzer held level. Maximum
difference in delivery quantity between injectors is 8.0 ml of fuel.
10.
If fuel delivery quantity differs between high and low levels by more than 8.0 ml, interchange
injectors and repeat test. If difference of delivery quantity changes with injectors, replace
injectors. If difference of delivery quantity does not change with movement of injectors, either
fuel lines are pinched or fuel distributor is defective.
11.
Check fuel injectors for leakage immediately after delivery quantity test is complete. Set sensor
plate in rest position. Activate fuel pump with jumper switch for 2 minutes. Injectors should not
drip. Replace injectors that drip.
See image. Fuel filter is probably located on the frame between the engine and fuel tank.

Is there gas in the tank? Many GM fuel gauges have shown half-full when in actuality, the tank has run dry. Check injector circuits with a noid light or regular test light to see if the light flashes. If the light flashes, but the injectors are not spraying, check fuel pressure with a gauge. If no fuel pressure, ensure that the fuel pump fuse is not blown (many GM cars have the fuel pump fuse in an inline fuse holder) If the fuse is good, check that the fuel pump is receiving power and ground (positive and negative) If it is, and there is still no fuel pressure, the pump is bad, and the gas tank will have to be dropped to get the pump out. Good Luck.

i'm pretty sure you have a Central Port Injection setup on this engine. Which means the injectors are inside of the upper plenum and cannot be seen. This type of fuel injection system uses a centrally located electric fuel injector(s) which feed fuel to a mechanical poppet style injector which is routed directly above the intake valves for each cylinder.

The poppet valves require a minimum of 56 psi of fuel pressure. If you have 55 psi it will not start. It needs the fuel pressure to overcome the mechanical resistance of the poppet injectors. Fuel pressure should at least be 60 psi. It is very important to check fuel pressure with an accurate gauge.

If fuel pressure is low it will not start no matter what you do and a new fuel pump will likley fix the problem. Get a good quality pump such as an a/c deco or Dephi. Other brands may be cheaper but they will not last.

If fuel pressure checks out good let me know and I'll give you some more info.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Sometimes there is a fuse just for the injectors if none of the injectors are firing id check the fuse.
But first check to see if the fuel injectors click because if they do click it could be the fuel pump.
Are you able to figure out what the fuel pressre is at when you prime the system? You can do this by checking the schrader valve on the fuel rail by plugging in a gauge and see if it has pressure when you turn the key.
if the injectors dont click and you have fuel pressure check the fuse for the fuel injector system (depending on model fuel injector system.) Cause you need to first make sure the fuel injectors arent firing cause it may be a pressure regulator problem or a fuel pump.
if you need further assistance or have a question about anything ive said please follow up with a comment and i will be glad to assist you further from there. Thanks and good luck.

Check your fuel pressure regulator. Remove the vacuum line attached to it and hook a fuel pressure gauge to the schrader valve on the fuel input line. The gauge should read at least 40 PSI, probably closer to 50-60 or more.

If it's lower than that, you're not getting enough fuel to the engine. It may also be stuck shut, meaning that you're putting in too much fuel.

If you find that the exhaust smells of fuel after cranking for awhile, there's a good chance that you're flooding out due to a faulty FPR.

check to see if your getting a pulse on the injectors
if it has the spider injector with a fuel pressure gauge check pressure see if it drops or have 55 to 66 psi check to see if also check the eng 1 fuse cgeck ecm 1 15amp

hi,you have to check your spray pattern of injector,then install a pressure gauge to check your fuel distributor for proper function, or perform a compression test to determine your engine,ty

You need to hook up a fuel pressure gauge to have an accurate reading on fuel pressure. Also one quick check is look in the oil cap and see if the rocker arms are moving when its cranked.