Description

Hyster S4.0FT, S5.5FT, S5.5FTS, H4.0FT5, H4.5FT6 Service Manual

If you have ever tried to tune an LPG forklift with a third-party manual, you know the pain. Wrong fuel pressure specs, missing bolt torque for the mixer, and no clue how the DEPR actually comes apart. This Hyster factory service manual for the S4.0FT, S5.5FT, S5.5FTS, H4.0FT5, and H4.5FT6 kills that guesswork cold. It is 34 pages of direct, step-by-step procedure written for the Kubota 3.8L SI engine LPG fuel system. No theory lectures. No generic diagrams. Just the sequence a trained Hyster tech follows. And it comes straight from the manufacturer – not a reprint.

LPG Tank and Bracket Replacement: Two Real Instructions

Under this header, the manual splits tank removal and installation into separate procedures. Pulling the tank looks straightforward on paper, but the bracket alignment pin removal is a step most guys skip – then wonder why the new tank rocks. The manual gives the exact removal sequence for the LPG tank bracket alignment pin on the S5.5FT model. You also get a dedicated install section for the bracket itself, which matters if you are swapping a damaged unit. Page references are given for the warning labels and block placement. Use blocks. The procedure says it; I say it.

Direct Electronic Pressure Regulator (DEPR) – What the Manual Lists

Section 5 covers the LPG fuel mixer with DEPR repair. Remove and install only – this is not a rebuild guide because the DEPR is a sealed unit. But the manual tells you the torque for the mounting bolts and the correct orientation of the mixer relative to the throttle body. That orientation detail is missing in every aftermarket copy I have seen. If you mix up the inlet and outlet, the engine leans out at idle. The manual keeps you out of that trap.

Control System Section – ECU and Low Level Sensor Work

Two subsections here: Engine Control Unit (ECU) and LPG Low Level Sensor. The ECU removal and install is straightforward – disconnect battery, unplug connectors, four bolts. The low level sensor, though, is where most DIY guys get burned. The wiring harness runs through a grommet that needs to be aligned during install. The manual shows the grommet position and the sensor orientation. Skip that, and you get a false low-fuel light or a leak path. Also, the control system section does not list diagnostic trouble codes; that is in a separate electronic service tool manual. But the physical swap procedure is correct for these Hyster models.

Why 34 Pages Matter for This LPG System

Thirty-four pages is tight. That tells you this manual is focused: fuel system, throttle body, exhaust, and control system. No engine overhaul. No transmission. Every page counts. For example, the LPG Fuel Filter Unit Repair section covers both the filter element and the housing. The housing disassembly includes a step to mark the orientation of the filter head before removal – a two-second action that saves you from installing a filter housing that leaks. The cleaner/inspect steps are written for shop conditions, not a clean room. They tell you to blow out the passages with compressed air at 30 psi. That is the kind of specific that keeps a job from turning into a comeback.

Source Authenticity: Factory Hyster vs. Aftermarket Reprints

Part number 4129471, 0900 SRM 1905. That is the Hyster document number. This is not a scanned and OCR’d copy from a third party; it is the official factory PDF as distributed by Hyster. The safety warnings on page 2 are verbatim from the OEM – includes the requirement to use Hyster approved parts. Aftermarket versions routinely strip out the warning about LPG fuel flammability or the block procedure. That gets people hurt. This manual keeps the full safety text. If you are working on an H4.0FT5 or H4.5FT6, you need the genuine torque values for the exhaust manifold and the O2 sensor (HEGO) install. Those numbers are in the exhaust section. Don’t guess.

Safety Precautions: What the Manual Forces You to Read

Page 2 is all warnings. Disconnect the battery ground cable. Use correct blocks. Wear safety glasses. Fasten a DO NOT OPERATE tag. The manual uses WARNING and CAUTION boxes with orange and yellow backgrounds. I have seen techs skip reading these because they think they know. Then they lift a counterweight without checking sling capacity. The manual tells you to verify crane, cables, and chains can support the load. That is not fluff – that is a life. This 34-page document puts those precautions right up front, not buried in an appendix.

FAQ – LPG Forklift Service Manual

Does this manual cover both the S4.0FT and the H4.0FT5 models?

Yes. The cover lists S4.0FT, S5.5FT, S5.5FTS, H4.0FT5, and H4.5FT6. The internal content references the Kubota 3.8L SI engine LPG system common to all these forklifts. If you have a different model, check the related manuals: Hyster LPG Fuel System 4.3L Engine Service Manual and Hyster Service Manual 8000 SRM 1409.

Are torque specifications listed for the fuel mixer bolts?

Yes. The LPG Fuel Mixer with DEPR section includes torque values for the mounting bolts. The manual does not give every fastener torque in the 34 pages; it focuses on fuel system and exhaust critical joints. For drivetrain fasteners, you will need a separate manual – we carry Hyster S/H Series Forklift Service Manual for that.

Can I use this manual for a propane conversion on a different engine?

No. The LPG system is specific to the Hyster Kubota 3.8L SI engine. Mixing components from other engines will cause incorrect fuel mapping and risk of fire. The manual explicitly warns against using non-Hyster approved parts. Stick to the listed models.

What types of fasteners are mentioned for the exhaust manifold install?

The exhaust manifold section covers removal and install of the manifold. It specifies to use new gaskets and torque the bolts in a sequence. The manual does not list a part number for the bolts, but it does tell you to inspect for corrosion and replace if needed. For transmission-related fasteners, refer to Manual Transmission documentation available separately.

If you are working on an S5.5FTS or an H4.5FT6 and need the factory procedure for the LPG low-level sensor or the electronic throttle body, this manual gets it done without the frustration of aftermarket noise. You get the OEM torque specs, the correct disassembly sequence, and the safety warnings that keep you upright. Do not trust a reprint. Manual Transmission manuals are also available, but for the LPG fuel system on these Hyster models, this is the only document you need.

Access the Factory Manual and get the genuine Hyster procedure for your S4.0FT, S5.5FT, S5.5FTS, H4.0FT5, or H4.5FT6 forklift today.